Calcium antagonists in N-methyl D-aspartate-induced retinal injury

Purpose: To detect the neuroprotective role of nimodipine and dantrolene in N-methyl-D-aspartate (NMDA)-induced retinal injury. Methods: In this study we used two calcium antagonists which have two different modes of action, nimodipine and dantrolene, to prevent NMDA-induced retinal ischemia in guinea pigs. In 40 animals we injected nimodipine (n=10), dantrolene (n=10), a combination of both (n=10) or sterile 0.9% NaCl solution as a placebo (n=10) before intravitreal injection of NMDA. We enucleated one eye of each animal after 48 hours and performed histopathologic examination. We also measured malondialdehyde (MDA) levels in retinal homogenates as a marker of ischemic injury. Results: Our results indicate that ganglion cells of the retina were preserved mostly by nimodipine, followed by combined nimodipine-dantrolene, and dantrolene respectively. The ganglion cell count was statistically significantly higher in cases where we used calcium antagonists than in the control group (p<0.05). We also found that MDA was significantly reduced by calcium antagonists compared to the control group (p<0.05). Conclusion: Our data show that nimodipine and dantrolene both have potential neuroprotective effects; nimodipine preserved retinal ganglion cells to a greater extent than dantrolene from NMDA-induced retinal injury.