动态观察谷氨酸浓度在围生期缺氧惊厥鼠脑内的变化及拉莫三嗪的神经保护作用

Dynamic change of glutamate concentration in the brains from neonatal rat pups with perinatal hypoxia-induced seizures and the neuroprotective of Lamotrigine

目的本次实验主要应用微透析技术动态监测生后10 d(P10)缺氧惊厥鼠脑内主要兴奋性氨基酸(EAAs)——谷氨酸(Glu)浓度的变化,观察其与惊厥的发生及远期脑损伤的关系,探讨拉莫三嗪(LTG)的神经保护机制。方法 66只P10新生鼠随机分成3组:缺氧-NS组(n=22);缺氧-LTG组(n=22)和常氧-NS组(n=22)。P10造模过程中,用微透析技术连续5 h动态监测鼠脑内Glu浓度;P29、30,Y-型电迷宫测试大鼠的学习和记忆能力;P30戊四氮测量大鼠的惊厥阈。结果 P10缺氧惊厥鼠脑内Glu浓度明显升高(P<0.01),缺氧240min降至最低点,但整个过程中Glu浓度均始终高于正常基础值(P<0.05)。预先注射LTG显著降低Glu的浓度(P<0.05)。P29时,缺氧-LTG组大鼠Y-型电迷宫测试中达到学会标准所需次数明显少于缺氧-NS组(P<0.01),24 h记忆保持率高于缺氧-NS组(P<0.01);缺氧-LTG组大鼠对戊四氮的惊厥阈值较缺氧-NS组明显增高(P<0.05)。结论围生期缺氧后出现脑内Glu浓度立即升高,并有持续升高效应,拉莫三嗪对其有抑制作用,并改善了缺氧惊厥鼠在发育期(P30)的学习和记忆能力,降低对致痫药物的敏感性。所以,拉莫三嗪可能通过迅速并持续降低Glu浓度,对围生期缺氧导致惊厥的动物模型起到远期的神经保护作用。

Objective To observe the correlation between the change of Glu concentration and the the onset of seizure based on the dynamic monitoring of the excitatory amino acids （EAAs） glutamate （Glu） in the brains from neonatal rat pups（ postnatal day 10, P10 ）, and evaluate the neuroprotective mechanism of Lamotrigine （LTG）. Methods Sixty-six P10 rat pups were randomly divided into three groups： Hypexia-NS group, Hypoxia-LTG group and Normoxia-NS group （ normal control group） with 22 rats in every group. The glutamate concentration in P10 rats with hypoxia-induced seizures were tested dynamicly for five hours by microdialysis methods. The ability of learning and memory with Y-maze test was estimated at P29 and P30. The seizure susceptibility by pentylenetetrazol （PTZ） was tested at P30. Results A clear ele- vation of glutamate concentration in Hypoxia-NS group P10 model rats which suffering from hypoxia immediately was ob- served（P 〈0.01 ）. The glutamate concentration decreased to the lowest level in 240 min after perinatal hypoxia, but the glutamate concentration was always higher than the normal basal data in the whole course （ P 〈 0.05 ）. The pretreatment with lamotrigine LTG lowered the glutamate concentration remarkably （ P 〈 0.05 ）. At P29, the rats in th eHypoxia-LTG group needed less training frequencies to learn the standard than rats in the Hypoxia-NS group（ P 〈0. 01 ） ,and the rates of 24 hour retention of memory in the Y-maze test were higher than that in the Hypoxia-NS group （P 〈 0.01 ）. At P30, the Vl＇Z-induced seizure thresholds of LTG-treated rats were higher than that in Hypoxia-NS group （P 〈 0. 05 ）. Conclusions A fast and persistent elevation of glutamate concentration in P10 rat brains after perinatal hypoxia can be observed. LTG can inhibit the increasing of glutamate concentration in P10 rats after suffering hypoxia, and improve the competence of learning and memory, and decrease the seizure susceptibility by chemical convulsant induction. All the re- suits and indications suggest that LTG has the potential long lasting neuroprotective effect probably by lowering the gluta- mate concentration on this particular animal model of perinatal hypoxia-induced seizures persistently.