PROTECTIVE EFFECT OF SPREADING DEPRESSION AGAINST NEURONAL DAMAGE FOLLOWING CARDIAC-ARREST CEREBRAL-ISCHEMIA

Effect of spreading depression (SD) on survival of CA1 hippocampal neu rons was studied in Sprague-Dawley rats subjected to cardiac arrest ce rebral ischaemia (CACl). SD was induced either by the topical applicat ion of KCl to the cerebral cortex (CSD) or by KCl perfusion of the hip pocampus via a microdialysis cannula (HSD). CACl was carried out by in trathoracic compression of major cardiac vessels at 1, 3 and 7 days af ter CSD induction and 3 days after HSD, following which neuronal loss in the CA1 sector of the hippocampus was determined morphometrically. Our study revealed the significant protective effect of SD on survival of the CA1 pyramidal neurons in rats which were subjected to CACl 3 d ays later. No significant indication of a protective effect was observ ed in animals with SD induced 1 or 7 days prior to CACl nor in rats in which KCl was substituted by NaCl of equivalent concentration which d id not induce any SD waves. Microdialysis assay during HSD showed a si gnificant elevation of extracellular glutamate. Our studies, demonstra ting an induction of a transitory period of neuronal resistance to isc haemia by preceding spreading depression, open an opportunity for eluc idation of endogeneous factors responsible for the development of such resistance.