A novel adamantane derivative attenuates retinal ischemia–reperfusion damage in the rat retina through σ1 receptors

The effects of a novel N-methyladamantan-1-amine derivative [(−)-MR22] with high σ1 receptor affinity were investigated on retinal degeneration using a rat model of ischemia–reperfusion injury. The animals were anaesthetized and retinal ischemia was induced by elevating the intraocular pressure to 120 mm Hg for 45 min. The drug was injected intraperitoneally before the ischemic damage. Retinal biochemical changes, i.e. increase of lactate content and decrease of glucose and ATP were significantly inhibited by the new and selective σ1 receptor ligand compared to the ischemic control group. The effect of (−)-MR22 was antagonized by pre-treatment with the σ1 site antagonist. The protective effect of (−)-MR22 on ischemic retina was confirmed by the histological analysis. These findings suggest that (−)-MR22 serves as a retinal neuroprotective agent and acts as a σ1 receptor agonist.