The Change And Meaning Of Mitochondrial Permeability Transition And Cytochrome C After Brain Ischemic Preconditioning In Rats

Objective: To investigate the effect of ischemic preconditioning on neural function, mitochondrial permeability transition and level of cyto- chrome C in the hippocampal tissue, in order to study further the brain protection mechanism produced by ischemic preconditioning.Methods: 48 male SD rats (weight 230-300g) were randomly divided into 4 groups: false operation group(n=12), ischemic preconditioning group(n=12), ischemia group(n=12), ischemia after ischemic precondition- ing group (n=12). False operation group: sew up the skin after exposing the common carotid artery (CCA) in right. Ischemic preconditioning group: a focal-focal cerebral ischemia model was induced by adopting the thread embolism method according to Longa with a little alteration. After blocking MCA blood flow for 30 minutes, the thread was pulled out, and the ECA nub was ligated.Ischemia group: a thread was directly inserted to MCA in the right side for 24 hours. Ischemia after ischemic preconditioning group: the procedure is similar to ischemic preconditioning , then 24 hours later, a thread was inserted to ACA in the right side through CCA in 24 hours. Ischemia group: a thread was inserted to MCA in the right side by a 24 hour brain ischemia.The following parameters were observed respectively in four groups: neural function according to Bederson method, HE dying , expression of cytochrome C in the hippocampus and mitochondrial permeability transition (n=12 in each group).Results: The score of neural function was 0,0.25±0.20,2.24± 0.87,1.16±0.71 in false operation group,ischemic preconditioning group,ischemia group and Ischemia after ischemic preconditioning group respectively, and the difference was significant between ischemia after ischemic preconditioning group and ischemia group(p<0.05).The level of CytC expression was 10.2±2.67,12.5±3.9, 54.6±6.98 and 31.4±4.1 in four groups respectively, also, the difference was significant between Is- chemia after ischemic preconditioning group and ischemia group(p<0.05).The OD value of MPT was 0.568±0.083,0.547±0.098,0.298±0.077,0.427±0.113 in four groups respectively, the difference was significant between Ischemia after ischemic preconditioning group and ischemia group (p<0.05), but there was no significant difference between false operation group and ischemic preconditioning group(p>0.05).Conclusion:Our study shows that after schemic preconditioning, the score of neural function was better,the level of CytC expression was lower,the OD value of MPT was higher in the Ischemia after ischemic preconditioning group than those in the ischemia group. These indicate that ischemic preconditioning can obviously increase the tolerance to later severe ischemia injury. BIT may be derived by decreasing the MPT and declining the discharge of CytC.