Hydrogen sulfide attenuates NMDA-induced neuronal injury via its anti-oxidative activity in the rat retina.

Although hydrogen sulfide (H2S) is generally thought to be a toxic gas, it has been reported to protect various tissues against ischemia-reperfusion injury. In the present study, we histologically investigated whether H2S, using sodium hydrosulfide (NaHS) as its donor, had a protective effect on N-methyl-d-aspartate (NMDA)-induced retinal injury in the rat in vivo. Under ketamine/xylazine anesthesia, male Sprague-Dawley rats were subjected to intravitreal NMDA injection. NaHS (0.163-120 μmol/kg) was intraperitoneally administered 15 min before NMDA injection. Morphometric evaluation at 7 days after NMDA injection showed that intravitreal NMDA injection resulted in ganglion cell loss. NaHS dose-dependently prevented this damage. NaHS (120 μmol/kg) significantly decreased the numbers of TUNEL-positive, 4-hydroxy-2-nonenal-positive, and 8-OHdG-positive cells 12 h after NMDA injection. In another experimental series, we demonstrated that NaHS (120 μmol/kg) significantly reduced the retinal injury induced by intravitreal NOC12 (400 nmol/eye), which was a nitric oxide donor and reported to induce oxidative stress, in the retina, 7 days after intravitreal injection. These results suggested that H2S protects retinal neurons against the injury induced by intravitreal NMDA in rats in vivo. Anti-oxidative activity of H2S are possibly involved in underlying protective mechanisms.