15-A2t-Isoprostane (15-A2t-IsoP) is toxic to neurons. (a) Diagram depicting the formation of 15-A2t-IsoP via the oxidation of arachidonic acid and subsequent spontaneous dehydration of 15-E2t-IsoP. (b) Mature primary cortical neurons were exposed to increasing concentrations of 15-A2t-IsoP for 48 h, at which time cell death was assessed by measuring release of lactate dehydrogenase (LDH) into the cell media from dying neurons. NMDA (100 μM) was used as a positive control, as it induces total cell death in these cultures. Note that 15-A2t-IsoP induces cell death in a dose-dependent manner with an LD50 of 950 nM. (c) The oxidative stress-sensitive HT22 hippocampal cell line was exposed to 15-A2t-IsoP for 18 h, after which cell viability was assessed by measuring cellular MTT reducing capacity. Like primary neurons, HT22 cells are killed by 15-A2t-IsoP with an LD50 of 3 μM. Data in (b) and (c) represent the mean ± SEM of at least three separate experiments, each performed at least in triplicate. *p < 0.05 vs. control by one-way ANOVA.