Tumor Necrosis Factor-alpha and Calcium Permeable AMPA Receptors Mediate Retinal Ganglion Cell Death in Experimental Glaucoma

JORGE LUIS CUEVA VARGAS; INGRID OSSWALD; NICOLAS UNSAIN; PHIL BARKER; DEREK BOWIE; ADRIANA DI POLO

Congreso; ARVO 2011; 2011

The Association for Research in Vision and Ophthalmology

Purpose:The primary mechanism of retinal ganglion cell (RGC) damage in glaucoma is not well understood. Tumor Necrosis Factor Alpha (TNF-α) has emerged as a key regulator of neuronal glutamate receptors in the central nervous system. Here, we tested the hypothesis that TNF-α mediates RGC loss in experimental glaucoma by stimulating plasma membrane insertion of calcium-permeable AMPA receptors (CP-AMPAR) in these neurons. Methods:RGC retrograde labeling was carried out by application of DiI onto the superior colliculus. Ocular hypertension (OHT) was induced a week later by injection of hypertonic saline into an episcleral vein in Brown Norway rats. The expression of TNF-α and its receptors, TNFR1 and TNFR2, was examined by RT-PCR, western blots and immunohistochemistry. Cell surface CP-AMPAR were visualized using a cobalt (Co2+) staining technique. The following agents were independently injected into the vitreous chamber: i) the TNF-α inhibitor Etanercept; ii) the CP-AMPAR blockers GYKI 52466 or Philantotoxin 343 (PhTX); or iii) the caspase-8 inhibitor Z-IETD-FMK. RGC neuroprotection was evaluated by quantification of RGC soma and axons.