CORTICAL SPREADING DEPRESSION PROTECTS AGAINST SUBSEQUENT FOCAL CEREBRAL-ISCHEMIA IN RATS

The possibility that cortical spreading depression (CSD) may have neur oprotective action during subsequent focal cerebral ischemia was exami ned in rats. Three days before the imposition of focal cerebral ischem ia CSDs were elicited by applying potassium chloride (KCl) for 2 h thr ough a microdialysis probe implanted in the occipital cortex. Control animals were handled identically except that saline was infused instea d of KCI. Focal ischemia was produced by the intraluminal suture metho d and cortical and subcortical infarct volumes were measured 7 days la ter. Neocortical infarct volume was reduced from 124.8 +/- 49.5 mm(3) in the controls to 62.9 +/- 59.5 mm(3) in the animals preconditioned w ith CSD (p = 0.012), There was no difference between the two groups in the subcortical infarct volume or in CBF, measured by the hydrogen cl earance method, during or immediately after the ischemic interval. Our data indicate that preconditioning CSD applied 3 days before middle c erebral artery occlusion may increase the brain's resistance to focal ischemic damage and may be used as a model to explore the neuroprotect ive molecular responses of neuronal and glial cells.