褪黑素对小鼠心肺复苏后脑损伤的影响及其机制研究

Effects and mechanisms of melatonin on brain injury after cardiopulmonary resuscitation in mice

摘要:

目的 探讨褪黑素对小鼠心脏骤停（CA）、心肺复苏（CPR）后脑缺血、再灌注损伤的影响及其作用机制。方法 将44只雄性小鼠随机分为假手术组（8只）、模型组（18只）、褪黑素组（18只）。复制CA模型后褪黑素组小鼠给予褪黑素药物治疗（10 mg/kg）。术后第3天进行神经功能评分（9分法），并观察10 d存活率。CA模型复制后6 h取小鼠脑组织，通过Western blotting检测小鼠脑组织GRP78、Chop、p-PERK、p-eIF2a、ATF4蛋白相对表达量，应用ELISA测定丙二醛（MDA）水平，同时取血清测定乳酸脱氢酶（LDH）活性。苏木精-伊红染色评估脑组织海马CA1区损伤情况。结果 小鼠均复苏成功。各组小鼠体重、心率、平均动脉压、胸外按压时间、肾上腺素用量、自主呼吸恢复时间比较，差异无统计学意义（P >0.05）。各组小鼠术后10 d生存率比较，差异无统计学意义（P >0.05）。模型组神经功能评分较假手术组低（P <0.05），褪黑素组较模型组高（P <0.05）。模型组CA1区神经元细胞死亡数量较假手术组多（P <0.05），褪黑素组较模型组少（P <0.05）。模型组LDH活性、MDA水平较假手术组高（P <0.05），褪黑素组较模型组低（P <0.05）。模型组脑组织GRP78、Chop、p-PERK、p-eIF2α、ATF4蛋白相对表达量较假手术组高（P <0.05），褪黑素组较模型组低（P <0.05）。结论 褪黑素对CA、CPR脑缺血具有保护作用，其作用机制可能是通过PERK-eIF2α-ATF4信号通路抑制内质网应激。

Abstract:

Objective To investigate the effects and mechanisms of melatonin on cerebral ischemia-reperfusion (CIR) injury after cardiac arrest / cardiopulmonary resuscitation (CA/CPR) in mice.Methods A total of 44 male mice were randomly divided into sham operation group (n = 8), model group (n = 18) and melatonin group (n = 18). The melatonin group was given melatonin (10 mg/kg) treatment following the establishment of CA model. The neurological function score was determined on the 3rd day after operation, and the 10-day survival rate of mice was observed. Six hours after the operation, the brain tissues of the mice were collected, and the protein levels of GRP78, Chop, p-PERK, p-eIF2α, and ATF4 in the brain tissues were detected by Western blotting. The level of malondialdehyde (MDA) was determined by ELISA, and the serum activity of lactate dehydrogenase (LDH) was also determined. Hippocampal CA1 neuronal injury was assessed by hematoxylin and eosin staining.Results All the mice were successfully resuscitated, and there was no difference in the weight, heart rate, mean arterial pressure, chest compression duration, the dosage of adrenaline, or the time to recovery of spontaneous breathing among the groups (P > 0.05). The 10-day survival rate was also not different among the three groups (P > 0.05). Compared with the model group, the neurological function score of the sham operation group and melatonin group was higher (P <0.05). The number of neuronal cell deaths in the hippocampal CA1 area was increased in the model group compared with the sham operation group, and was decreased in the melatonin group relative to that in the model group (P < 0.05). The activity of LDH and the level of MDA were higher in the model group than those in the sham operation group and melatonin group (P < 0.05). In addition, the protein levels of GRP78, Chop, p-PERK, p-eIF2α, and ATF4 in the brain tissues were also higher in the model group compared with the other groups (P < 0.05).Conclusions Melatonin has a protective effect on brain injury of mice after CA/CPR. The mechanism may be that melatonin attenuates endoplasmic reticulum stress by inhibiting PERK-eIF2α-ATF4 signaling pathway.