孕酮对大鼠中枢神经系统发育期七氟醚神经毒性的作用

Neuroprotection of progesterone on neonatal rats after sevoflurane inhalation anesthesia

目的探讨孕酮对大鼠中枢神经系统发育期七氟醚神经毒性的作用及其机制。方法将健康新生SD大鼠随机分为3组(n=40,雌雄各20只):空白对照组(C组)、七氟醚组(S组)、孕酮+七氟醚组(S+P组)。S+P组大鼠出生后第4~9天注射孕酮[8 mg/(kg.d)],第7~9天注射孕酮后行七氟醚暴露(浓度3%,流量2 L/min,2 h/d);C组和S组大鼠出生后于相同时间点以相同方式注射等量溶剂,C组大鼠第7~9天行混合气体暴露(空气和氧气混合,流量2 L/min,2 h/d),S组大鼠第7~9天行七氟醚暴露(浓度3%,流量2 L/min,2 h/d)。采用TUNEL法检测大鼠海马组织CA1区神经细胞凋亡情况,Western blotting检测海马组织中凋亡蛋白Casepase-3的表达。采用Y迷宫、Morris水迷宫和跳台实验评价大鼠出生后第6周的空间认知能力。结果七氟醚可导致新生大鼠海马组织CA1区神经细胞凋亡和Casepase-3蛋白表达增加(P<0.01);应用孕酮可明显减少七氟醚导致的海马组织CA1区神经细胞凋亡,降低海马组织中Casepase-3蛋白表达(P<0.01)。Y迷宫、Morris水迷宫和跳台实验结果显示,七氟醚可降低大鼠的交替得分率(P<0.05),延长大鼠在Morris水迷宫中寻找平台所需时间(P<0.05),增加大鼠在跳台中的错误次数(P<0.01);应用孕酮可明显增高大鼠的交替得分率(P<0.05),缩短大鼠在Morris水迷宫中寻找平台所需时间(P<0.05),减少大鼠在跳台中的错误次数(P<0.01)。结论新生大鼠多次吸入七氟醚可引起中枢神经损伤并导致青年期认知损害,孕酮对七氟醚所致的新生大鼠中枢神经系统发育期神经毒性损伤可产生保护作用。

Objective To investigate the neuroprotection of progesterone on neonatal rats after sevoflurane inhalation anesthesia and its mechanisms.Methods A total of 120 newborn Sprague-Dawley rats were randomly divided into three groups(n=40):blank control group(group C),sevoflurane group(group S)and progesterone plus sevoflurane group(group S+P),half male and half female in each group.The rats in group S were exposed to 3%sevoflurane for two hours on postnatal days(P)seven,eight and nine,which was used to establish the developmental sevoflurane neurotoxicity model.The rats in group C were exposed to mixture of gases(2 L/min,2 hours a day).The rats in group S+P received a daily injection of progesterone(8 mg/kg)from P4 to P9 and then were exposed to 3%sevoflurane(2 L/min,2 hours a day)for 3 consecutive days between P7 to P9.The apoptosis of nerve cells in the CA1 area of the hippocampus evaluated by TUNEL assays in neonatal rats.The relative expression of apoptosis protein(caspase-3)in the hippocampus determined by Western blotting.Rats in each group evaluated for the space orientation ability and the learning and memory ability by Y maze,Morris water maze and platform test 6 weeks after birth.Results Sevoflurane significantly increased the neuronal apoptosis in CA1 area of the hippocampus in the central nervous system of newborn rats and increased the expression of Caspase-3 in the hippocampus(P<0.01);progesterone significantly reduces neuronal apoptosis which induced by sevoflurane and the expression of Caspase-3 in the hippocampus(P<0.01).The results of the Y maze,Morris water maze and platform test showed that sevoflurane reduced the alternating scoring rate of rats(P<0.05),prolonged the time required to find the platform in the water maze(P<0.05)and increased the number of errors in the platform test(P<0.01).Progesterone significantly increased the alternating scoring rate of rats(P<0.05),shortened the time required to find the platform in the water maze(P<0.05)and significantly reduced the number of errors in the platform test(P<0.01).Conclusion Repeated inhalation of 3%sevoflurane in neonatal rats can cause neurotoxic damage and induce cognitive dysfunction.Progesterone may have a neuroprotective effect on the neurotoxic damage of neonatal rats induced by sevoflurane.