Role of mitophagy in cognitive dysfunction in rats with sepsis-associated encephalopathy / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of mitophagy in cognitive dysfunction in rats with sepsis-associated encephalopathy (SAE).Methods:Twenty-four clean-grade healthy male Sprague-Dawley rats, aged 13-14 weeks, weighing 230-250 g, were divided into 3 groups ( n=8 each) using a random number table method: sham operation group (Sham group), SAE group and SAE+ autophagy inhibitor 3-methyladenine (3-MA) group (3-MA group).The SAE models were developed by cecal ligation and puncture in anesthetized animals.3-MA 10 mg/kg was intraperitoneally injected at 30 min after developing the model in 3-MA group.Cognitive function was assessed by Morris water maze test, and the escape latency and ratio of the time of staying at the target quadrant were recorded.After the end of Morris water maze test, the rats were sacrificed and hippocampal tissues were collected for microscopic examination of the pathological changes which were scored after hematoxylin-eosin staining and for determination of the expression of autophagy-related proteins LC3, Beclin1 and p62 (by Western blot).The ratio of LC3Ⅱ/LC3Ⅰwas calculated.The hippocampal mitochondria were isolated to measure mitochondrial membrane potential (MMP), ATP content and ATPase activity by spectrophotometry. Results:Compared with Sham group, the escape latency was significantly prolonged, the ratio of the time of staying at the target quadrant was decreased, the pathological score of hippocampus was decreased, and the contents of MMP and ATP and ATPase activity were decreased in SAE and 3-MA groups, the ratio of LC3Ⅱ/LC3Ⅰwas significantly increased, the expression of Beclin1 was up-regulated, and the expression of p62 was down-regulated in SAE group, and the ratio of LC3Ⅱ/LC3Ⅰwas significantly decreased, and the expression of Beclin1 and p62 was up-regulated in 3-MA group ( P<0.05).Compared with SAE group, the escape latency was significantly prolonged, the ratio of the time of staying at the target quadrant was decreased, the pathological score of hippocampus was decreased, the ratio of LC3/LC3Ⅰwas decreased, the expression of Beclin1 was down-regulated, the expression of p62 was up-regulated, and the contents of MMP and ATP and ATPase activity were decreased in 3-MA group ( P<0.05). Conclusions:Hippocampal mitophagy is involved in cognitive dysfunction in the rats with SAE.