Neuroprotective effects of FK506 against excitotoxicity in organotypic hippocampal slice culture

FK506 has been originally classified as an immunosuppressant and is known to exhibit neurotrophic actions in vitro and protective effects on some neurological conditions. We investigated the neuroprotective effects of FK506 on kainic acid (KA)-induced neuronal death in organotypic hippocampal slice cultures (OHSCs). After an 18 h KA (5 μM) treatment, significantly neuronal death was detected in the CA3 region using propidium iodide staining. However, neuronal death was significantly prevented at 24 and 48 h after treatment with 0.1 μM FK506. Using cresyl violet staining, we also observed that an increased number of CA3 neurons survived in the 0.1 μM FK506 group compared to the KA only group. Based on the results of the Western blot analysis, the expressions of 5-lipoxygenase and caspase-3 were reduced 24 h after 0.1 μM FK506 treatment. The levels of superoxide dismutase (SOD) and phospho-Akt expression were increased by treatment with 0.1 μM FK506. These results suggest that FK506 may have a positive role in protecting neurons against cell death in the KA injury model of OHSCs.