GYY4137, an extended-release hydrogen sulfide donor, reduces NMDA-Induced neuronal injury in the murine retina

We previously reported that systemic administration with sodium hydrogen sulfide, a rapid-release donor compound of hydrogen sulfide (H₂S), protected retinal neurons against N-methyl-D-aspartic acid (NMDA)-induced injury. For clinical application of H₂S donors for retinal neurodegeneration, topical administration with an extended-release donor compound will be better. In the present study, we histologically investigated whether GYY4137, an extended-release hydrogen sulfide donor, had a protective effect on NMDA-induced retinal injury in the mice in vivo. Male and female B6.Cg-Tg(Thy1-CFP)23Jrs/J and C57BL/6J mice anesthetized with a mixture of ketamine and xylazine were subjected to intravitreal NMDA injection (80nmol/eye). GYY4137 was intravitreally administered with NMDA simultaneously. Morphometric evaluation was carried out seven days after NMDA injection. Intravitreal NMDA induced retinal ganglion cell loss. GYY4137 (1, 10 and 100nmol/eye) significantly reduced retinal ganglion cell loss seven days after NMDA injection. GYY4137 (10nmol/eye) decreased the numbers of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL)-positive and 8-hydroxy-2-deoxyguanosine (8-OHdG)-positive cells 12h after NMDA injection. These results suggest that extended release donor compounds of H₂S protect retinal neurons against excitotoxicity induced by intravitreal NMDA in the mice in vivo through its anti-oxidative activity.