Neuroprotective effects of sigma-1 receptor agonists against beta-amyloid-induced toxicity

Prolonged exposure of cultured cortical neurons to the residue 25-35 fragment of β-amyloid protein, in the presence of dizocilpine, an antagonist of the N-methyl-D-aspartate receptor, and of 6,7-dinitroquinoxaline-2,3-dione, an antagonist of α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors, resulted in the expression of the proapoptotic protein Bax and neuronal death. Beta-amyloid protein(25-35)-induced neuronal death was substantially attenuated by the σ1 receptor agonist 2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate. The neuroprotective action of 2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate was mimicked by the σ1 ligand methyl (1S,2R)-2-[1-adamantyl(methyl)amino]methyl-1-phenylcyclopropanecarboxylate and was antagonized by the σ1 receptor antagonist N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)-phenyl]-ethylamine monohydrochloride. These results suggest that σ1 receptor agonists might function as neuroprotectant agents in Alzheimer's disease.