Abstract
Purpose: :
A novel synthetic Dehydroepiandrosterone analogue has previously investigated for its possible anti-apoptotic role in retinal detachment induced apoptosis (ARVO 2010). In this study we evaluate the neuroprotective role of this molecule in two critical time points post RD (3 and 7 days) and investigate the effects of this DHEA-Analogue in retinal glial cells and astrocytes after systemic submission in an experimental model of retinal detachment. Macrophage infiltration and caspase-3 expression was also studied.
Methods: :
Adult Sprague Dawley rats underwent retinal detachment. Animals were injected with the synthetic DHEA analogue (one injection every day) and sacrificed three and seven days post RD by transcardial perfusion. Animals received intraperitonealy 10 mg of the analogue per injection. The eyes were enucleated and prepared for cryoprotection and immunohistochemistry. The primary antibodies that we used were Anti-Vimentin for Müller cells, anti-GFAP for astrocytes, anti-Rhodopsin for Rods Photoreceptors, anti-CD68 for macrophages and anti-Caspase-3 for Caspase-3 activity. TUNEL staining was performed in order to evaluate the apoptotic rate. Specimens were analyzed under confocal microscopy. ONL thickness 7 days post RD was measured with optical microscopy.
Results: :
RD resulted in induced photoreceptor apoptosis especially three days post RD. Treatment with DHEA analogue reduced significantly the TUNEL positive cells in the ONL. Seven days post RD, photoreceptors cell death appeared lower in all animals, but in DHEA Analogue treated animals photoreceptor apoptotic cell death was almost reversed. Caspase-3 activation and macrophage infiltration were also decreased after treatment with DHEA Analogue at 3 and 7 days after RD. In treated animals, gliosis (Vimentin positive cells) was significantly reduced three days after RD while at 7 days the distribution of Vimentin was more ordered. Astrocytes (GFAP positive cells) also appeared in lower numbers in treated animals at 3 and 7 days after RD but the differences from non-treated animals were less prominent. DHEA-Analogue prevents the reduction of the ONL thickness at 7 days post RD. This result was also confirmed with Rhodopsin immunohistochemistry.
Conclusions: :
Our results suggest that this molecule might plays an anti-apoptotic role in retinal detachment induced apoptosis and possibly indicates a promising candidate for future clinical neuroprotection studies. DHEA-Analogue could prevent the retina from infiltration, gliosis and Caspase-3 mediated apoptotic cell death. In future experiments we plan to explore the apoptotic pathway involved in this neuroprotective approach.
Keywords: neuroprotection • retinal degenerations: cell biology • retinal detachment