[Cerebral ischemic tolerance induced by focal ischemic preconditioning in rats].

OBJECTIVE: To investigate the ischemic tolerance induced by focal ischemic preconditioning (PC) in rats.

METHODS: Ten minutes of middle cerebral artery occlusion(MCAO) was used for PC. Different duration of reperfusion (1, 3, 7, 14, 21 and 28 days) was allowed before 2 hours of MCAO followed by 22 hours of reperfusion in SD rats that were divided into the PC group and the PC plus MCAO group, and were compared with the rats of sham-operation plus MCAO group. Neurological scores, infarct volume, brain water content and HE staining were evaluated in each group.

RESULTS: PC produced no neurological deficits and TTC-demonstrated infarct. PC reduced neurological deficits significantly caused by 2 h MCAO 1-28 days after PC. Infarct volume was reduced only if PC was performed 1-14 days before MCAO. PC given 3 days before MCAO also decreased brain water content.

CONCLUSION: Ten minutes of MCAO was strong enough to induce ischemic tolerance without brain injury. Infarct volume reduction appeared at 1 day and did not vanish until 14 days after PC, but protection against neurological impairment existed at least 4 weeks.