Effects of isoflurane postconditioning on mitochondrial permeability transition pore in brain tissues of neonatal rats with hypoxic-ischemic brain injury / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of isoflurane postconditioning on mitochondrial permeability transition pore (mPTP) in brain tissues of neonatal rats with hypoxic-ischemic brain injury.Methods One hundred and twenty 7-day-old Sprague-Dawley rats,weighing 12-16 g,were randomly divided into 4 groups (n =30 each) using a random number tablesham operation group (group S),isoflurane group (group I),hypoxicischemic brain injury group (group HIBI),and hypoxic-ischemic brain injury + isoflurane postconditioning group (group HI).To establish hypoxic-ischemic brain injury model in the neonatal rats,the left common carotid artery ligation was carried out,and then the rats were exposed to 8％ O2 + 92％ N2 at 37 ℃ for 2 h in HIBI and HI groups.The rats inhaled 1.5 ％ isoflurane for 30 min after the model was established in group HI.The rats only inhaled 1.5％ isoflurane for 30 min in group I.At 24 h after the model was established,10 rats taken out randomly in each group were sacrificed and brains were removed to detect mPTP opening.At 7 days after the model was established,the survival rate was recorded in the rest rats.The rats were then sacrificed and brains were removed and the right and left cerebral hemispheres were weighed separately,and the ratio between left/right cerebral hemispheres was calculated.The density of normal neurons in ventral posterior inferior thalamic nucleus and hippocampal CA3 region in the left and right cerebral hemispheres were measured and the ratios of the density of normal neurons in the left to right cerebral hemisphere were calculated.Results There was no significant difference in the survival rate between the four groups (P ＞ 0.05).Compared with group S,the ratios of the density of normal neurons in the left to right cerebral hemisphere,weight of left cerebral hemisphere,and ratio between left/right cerebral hemispheres were significantly decreased,and mPTP opening was increased in group HIBI (P ＜ 0.05),and no significant changes were found in the parameters mentioned above in group I (P ＞ 0.05).Compared with group HIBI,the ratios of the density of normal neurons in the left to right cerebral hemisphere,weight of left cerebral hemisphere,and ratio between left/right cerebral hemispheres were significantly increased,and mPTP opening was decreased in group HI (P ＜ 0.05).Conclusion The mechanism by which isoflurane postconditioning reduces hypoxic-ischemic brain injury may be related to inhibition of mPTP opening in brain tissues of neonatal rats.