A new model of ischemic preconditioning using young adult hippocampal slice cultures

In ischemic preconditioning (IPC), brief sublethal ischemia protects neurons from a subsequent lethal ischemia. In vivo models faithfully display preconditioning, yet, these models are technically challenging, time-consuming and expensive. In vitro models of preconditioning have also been developed that are technically easier and less expensive. A drawback of pre-existing in vitro models is that since susceptibility to ischemic injury is age-dependent; neuroprotection is being studied in neurons that have intrinsic resistance to oxygen-glucose deprivation (OGD). This study introduces a new in vitro model of ischemic preconditioning in hippocampal slice cultures isolated from 20-30-day-old rats. Slice cultures show a high susceptibility and sharp thresholds toward ischemia that is comparable to that found in vivo. A 5-min OGD treatment was not neurotoxic to young adult slice cultures, while a 10-min OGD treatment was neurotoxic. In addition, the sublethal 5-min OGD treatment protected against a 10-min OGD treatment that was delivered 24 h later. Neuroprotection was seen in preconditioned slice cultures stained with propidium iodide (PI) or with antisera against the neuron-specific antigen NeuN. Energy failure is hypothesized to trigger ischemic preconditioning and a 5-min OGD treatment induced transient energy failure in young adult slice cultures. This model may assist in the search for new therapeutics for the prevention and/or treatment of stroke.