Dynamic aspects of cerebral hypoxic preconditioning measured in an in vitro model

Preconditioning increases the neurons' resistance to subsequent hypoxia. An in vitro study was conducted to explore kinetic aspects of hypoxic preconditioning. Hippocampal slices were exposed to one single or repeated episodes of oxygen and glucose deprivation (OGD). The interval between OGD episodes varied between 30 min and 180 min. OGD led to a significant reduction in the population spike amplitude. Subsequent episodes of OGD did not result in a further reduction in the population spike amplitude if the interval between the episodes was ca. 60 min, which demonstrated that there were preconditioning effects. In the experiment using an interval of 30 min, population spike amplitude decreased after each OGD episode. The set-up described is useful for detecting damaging effects of OGD as well as preconditioning effects. A time window of ca. 60 min is required to induce protective mechanisms.