# Effects of a ROCK Inhibitor on Retinal Ganglion Cells In Vivo and In Vitro

## TL;DR

This study shows that a ROCK inhibitor called Y-27632 protects retinal ganglion cells in both lab and animal models, possibly through a mechanism unrelated to eye pressure.

## Contribution

The study demonstrates the IOP-independent neuroprotective effects of Y-27632 on retinal ganglion cells in vivo and in vitro.

## Key findings

- Y-27632 increased RGC survival by 6.3% in vivo and 1000 nM Y-27632 improved survival in vitro.
- Y-27632 reduced intraocular pressure by 18.3% in the mouse model.
- OCT and ERG data confirmed the neuroprotective effects of Y-27632 in retinal tissues.

## Abstract

Objective: To investigate the neuroprotective effects of a Rho-associated kinase (ROCK) inhibitor on retinal ganglion cells (RGCs) in vitro and in vivo. Methods: For in vivo studies, a unilateral optic nerve crush mouse model was established. Then, 100 mM Y-27632 (a ROCK inhibitor) or saline was applied to the experimental eyes once a day for 14 days. The effects of the ROCK inhibitor were evaluated by counting the surviving RGCs in the enucleated flat retina tissues and measuring the inner retinal thickness using optical coherence tomography (OCT), the amplitude of the electroretinogram (ERG), and the change in intraocular pressure (IOP). For the in vitro study, RGCs were isolated from five-day-old mice using a modified immunopanning method with magnetic beads. The isolated RGCs were incubated for 72 h with various concentrations of Y-27632, after which TUNEL assays were performed to determine the number of surviving RGCs. Results: Y-27632 has neuroprotective effects, as it significantly increased the number of surviving RGCs by approximately 6.3%. OCT and ERG data also revealed that Y-27632 induced neuroprotective effects in vivo; furthermore, Y-27632 reduced IOP by approximately 18.3%. The in vitro study revealed the dose-dependent neuroprotective effects of Y-27632, with the highest dose of Y-27632 (1000 nM) increasing the RGC survival rate after 72 h of incubation compared with that of the control. Conclusions: The ROCK inhibitor Y-27632 may exert some neuroprotective effects on RGCs when it is used as an eye drop through an IOP-independent mechanism.