Glutathione content is altered in Müller cells of monkey eyes with experimental glaucoma

Extracellular levels of glutamate are thought to be increased in glaucoma and thus contribute to retinal damage. An increase in glutamate concentration or duration in the extracellular retinal space is expected to impact glutathione content in Müller cells since glutamate is the rate-limiting constituent in glutathione synthesis. We have investigated whether glutathione content is changed in retinal Müller cells of monkeys with experimental glaucoma using immunocytochemistry and image analysis. Müller cells in glaucomatous retinas showed significantly greater immunoreactivity (27-57%) for glutathione than those in fellow control retinas, increasing with the duration of elevated intraocular pressure (IOP). This pattern of labeling was prominent in all four monkeys studied. The presence of more glutathione in Müller cells of glaucomatous retinas is consistent with an increase in extracellular glutamate and an increase in transport and metabolism of glutamate.