Objective To investigate long-term brain protective effect and mechanism of isoflurane postconditioning on hypoxic-ischemic brain injury(HIBI) in neonatal rats.Methods 105 Sprague-Dawley(SD)neonatal rats were randomly divided into sham surgery group , model group , isoflurane group , atractyloside group , atractyloside with isoflurane group , cyclosporine group and cyclosporine with isoflurane group .Each group had left common carotid arterial ligation ( sham group threading without ligation ) followed by 8% oxygen and 92% nitrogen mixed gas .After model was established ( or sham surgery), injected drug in lateral ventricle: two atractyloside group were injected atractyloside , two cyclosporine group were injected cyclosporine A , other groups were injected saline .1.5%isoflurane were inhaled in isoflurane process-ing group for 30 min.Evaluating cognitive function by Morris water maze test (MWM) in the 30th to 35th days.Neuronal density ration in thalamic ventral posteromedial nucleus and hippocampal CA 3 region of left to right cerebral hemisphere were calculated after the MWM .Results Compared with sham surgery group , the average escape latency time and swim-ming routes was longer(P<0.05), while the number of crossing platform, the percentage of platform quadrant time and platform quadrant routes were reduced in model group , two atractyloside group , and there was no significant difference in isoflucane group and two cyclosporine group , while neuronal density ration were reduced(P<0.05)in other groups.Com-pared with model group, the average escape latency time and swimming routes were shorter (P<0.05), while the number of crossing platform , the percentage of platform quadrant time and platform quadrant routes and neuronal density ration were increased(P<0.05)in isoflurane group and two cyclosporine group .While there was no significant difference in above in-dex in two atractyloside group(P>0.05).Compared with isoflurane group, the average escape latency time and swimming routes were longer ( P<0 .05 ) , while the number of crossing platform , the percentage of platform quadrant time platform quadrant routes and neuronal density ration were reduced (P<0.05) in two atractyloside group(P<0.05),and there was no significant difference in two cyclosporine group (P>0.05).Conclusion Isoflurane postconditioning has long-term pro-tective effect on reducing HIBI neonatal rats , and the mechanism may be by inhibiting the openness of mPTP .%目的：探讨异氟醚后处理对缺血缺氧性脑损伤（ HIBI）新生大鼠的长期脑保护作用及机制。方法将105只新生SD大鼠随机分为假手术组、模型组、异氟醚、苍术苷组、苍术苷＋异氟醚组、环孢素组、环孢素＋异氟醚组，每组各15只。除假手术组外其余各组均制作HIBI模型。模型建立后侧脑室注射药物：苍术苷组、苍术苷＋异氟醚组注射线粒体通道转换孔（ mPTP）特异性开放剂苍术苷；环孢素组、环孢素＋异氟醚组注射mPTP特异性抑制剂环孢素A；其余组注射生理盐水；在此基础上各异氟醚组予异氟醚后处理：吸入含1．5％异氟醚的湿化混合气体30 min，2 L／min。干预后30～35 d行Morris水迷宫试验，评估大鼠学习记忆功能；计数丘脑腹后内侧核和海马CA3区左、右侧正常神经元密度比值。结果与假手术组比较，模型组及苍术苷组、苍术苷＋异氟醚组平均逃逸潜伏期延长，穿平台次数、平台象限时间百分比、平台象限路程百分比降低（P均＜0．05）；各组丘脑腹后内侧核及海马CA3区左、右侧神经元密度的比值均降低（ P＜0．05）。与模型组比较，异氟醚组、环孢素组、环孢素＋异氟醚组平均逃逸潜伏期缩短，穿平台次数、平台象限时间百分比、平台象限路程百分比、丘脑腹后内侧核及海马CA3区左、右侧神经元密度比值升高（ P均＜0．05）。与异氟醚组比较，苍术苷组、苍术苷＋异氟醚组平均逃逸潜伏期延长次数、平台象限时间百分比、平台象限路程百分比、丘脑腹后内侧核及海马CA3区左、右侧神经元密度比降低（ P均＜0．05）。结论异氟醚后处理对HIBI新生大鼠具有长期脑保护作用，其机制可能为抑制mPTP开放。
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