Effect of hydrogen sulfide donors on intraocular pressure in rabbits

Purpose: In this study, we investigated the effect of a slow-releasing hydrogen sulfide (H₂S) donor, GYY 4137, on intraocular pressure (IOP) in normotensive rabbits. Furthermore, we compared the IOP-lowering action of GYY 4137 with those elicited by other H₂S-producing compounds, l-cysteine and ACS67 (a hybrid compound of latanoprost with an H₂S-releasing moiety). Methods: IOP was measured in New Zealand normotensive male albino rabbits using a pneumatonometer (model 30 classic; Reichert Ophthalmic Instruments, Depew, NY). At 0 h, 50 μL of test compounds were applied topically to 1 eye of each animal, while the contralateral eye received the same quantity of vehicle (saline). IOP was measured hourly until baseline IOP readings were attained and animal eyes monitored for potential side effects (i.e., tearing, hyperemia). Results: GYY 4137 (0.1%-2%) produced a dose-dependent decrease in IOP reaching a maximum of 27.8% ± 3.14% (n = 5) after 6 h. Interestingly, a significant contralateral effect was observed in vehicle-treated controls eyes at all doses tested. l-cysteine (5%) and ACS67 (0.005%) also elicited a significant (P <0.01) decrease in IOP that achieved a maximum of 28.84% ± 1.53% (n = 5) and 23.27% ± 0.51% (n = 5), respectively, after 3 h. All 3 H₂S-producing compounds also caused a significant contralateral effect in vehicle-treated control eyes. Conclusion: We conclude that GYY 4137 and other H₂S-producing donors can reduce IOP in normotensive rabbits. However, the profile of IOP-lowering action of GYY 4137 was different from the other H₂S donors affirming its ability to act as a slow-releasing gas donor.