Valproic acid prevents NMDA-induced retinal degeneration in marmosets

Valproic acid (VPA) is a prescribed drug widely used for treatment of epilepsy, mood disorders, migraines and neuropathic pain. Accumulating evidence suggests that VPA possess neuroprotective properties. Glaucoma, one of the leading causes of vision loss in the world, is characterized by progressive degeneration of retinal ganglion cells (RGCs) and their axons. Intravitreal injection of N-methyl-D-aspartate (NMDA) is well studied in rodents as an acute model of RGC death. In the present study, we first investigated whether NMDA induced retinal degeneration in non-human primate common marmosets as the structure and function of the eye is similar to that of humans. We found that NMDA had no effects on intraocular pressure but induced retinal degeneration by using optical coherence tomography and multifocal electroretinogram, both of which are non-invasive methods. In addition, VPA treatment suppressed acute retinal degeneration and ameliorated visual impairment in marmosets. Our findings raise intriguing possibilities that VPA may be useful for preventing RGC death and suggest that the marmoset is a useful animal model for studying glaucoma.