Abstract
Recent evidence that apoptosis, programmed cell death, is at least partially involved in delayed neuronal death, prompted us to hypothesize that selective and vulnerable death in the hippocampal CAl sector may work in the direction of attenuating brain damage caused by further ischemic insults occurring in the future. Employing gerbils, we examined whether or not preconditioning with 5-min forebrain ischemia can ameliorate mortality and cell damage caused by 15-min forebrain ischemia given 10 days later. In a previous study, we found that gerbils preconditioned with 5-min forebrain ishcemia had a significantly attenuated mortality and body weight loss after 15-min forebrain ischemia, although the pathological findings for the brain tissues from 14-day survivors did not reveal any significant differences between the nonpreconditioned group and preconditioned group. In the present study, therefore, we examined the brain edema and pathological changes in gerbils at the time point when it was not yet known whether the asimals would die or survive. The brain edema at 2 hours, 2 days and 7 days after 15-min forebrain ischemia was significantly reduced in the preconditioned group (p<0.01). The pathological findings obtained by the Gallyas staining method also demonstrated less severe cell damage in the cerebral cortex and hypothalamus in the preconditioned group. The present data indicated that the ameliorating effect of preconditioning with 5-min forebrain ischemia on the mortality and body weight loss was well correlated with an attenuation of edema formation and cell damage in the brain.
