Neuroprotective Effects of Exoenzyme C3 Transferase in Excitotoxic Optic Neuropathy

Abstract

Purpose: : To evaluate the neuroprotective effects of exoenzyme C3 transferase (C3) on N-methyl-D-aspartate (NMDA)-induced neurotoxicity in the rats.

Methods: : C3 was expressed in E.coli, purified by affinity chromatography, and injected intravitreally into rat eyes treated with or without NMDA. At various time points after injection, eyes were nucleated. Western blot analysis of Rho levels was performed on homogenized retinas to confirm Rho inhibition by C3. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and cresyl violet staining were performed on retina flat-mounts. TUNEL positive cells or cresyl violet-stained cells were counted. Hematoxylin/eosin (HE) staining was also performed on retina cross-sections for morphological analysis.

Results: : Western blot showed that Rho expression in rat retinas was inhibited for 2 days after intravitreal injection of C3. Intravitreal injection of NMDA induced apoptosis of neurons within the ganglion cell layer (GCL), accompanied by reduction of cell density in the GCL and decrease in inner plexiform layer (IPL) thickness. Co-injection of C3 reduced retinal ganglion cell (RGC) apoptosis, and increased neuronal density in the GCL and IPL thickness.

Conclusions: : C3 protected the retina from excitotoxicitic damages induced by NMDA.

Keywords: neuroprotection • ganglion cells • apoptosis/cell death