重复经颅磁刺激对慢性应激抑郁模型大鼠行为及海马神经元凋亡的影响

Effect of repetitive transcranial magnetic stimulation on the improvement of behaviors and neuronal apoptosis in rats with chronic stress induced depression

目的 探讨重复经颅磁刺激（repetitive transcranial magnetic stimulation,rTMS）对慢性应激抑郁模型大鼠抑郁样行为的改善作用及对海马神经元凋亡的影响.方法 40只雄性SPF级SD大鼠经过筛选后其中38只随机分为2组,分别为对照组（n=8）和造模组（n=30）,造模组应用孤养联合慢性不可预见性温和应激（chronic unpredictable mild stress,CUMS）方法建立大鼠抑郁模型,剔除造模不成功的大鼠,将造模成功的24只大鼠分为三组：模型组（n=8,不给予任何处理）、rTMS组（n=8,给予10 Hz的rTMS干预）和伪刺激组（n=8,模拟rTMS环境而没有rTMS刺激发出）.各组大鼠分别于造模前、造模后和干预后采用体质量测量、蔗糖水消耗实验和旷场试验检测大鼠行为学的改变,采用尼氏染色法检测大鼠海马神经元的大小、形态和数目的变化,采用免疫组织化学方法检测大鼠海马神经元凋亡蛋白Bax的表达变化.结果 （1）行为学结果显示：应激可以使大鼠行为学评分显著降低（均P＜0.05）,rTMS干预可以显著改善其行为学评分（均P＜0.01）;与模型组相比,rTMS组大鼠体质量减分率（0.32±0.05）％、蔗糖水消耗实验评分（7.03±1.02）分、旷场实验的水平运动评分（8212.41±1416.15）分以及垂直运动评分（8.75± 1.58）分均显著增高,差异具有统计学意义（均P＜0.01）.（2）尼氏染色结果显示：应激21d导致大鼠海马CA3区神经元损伤,细胞形态差,尼氏小体数目减少;rTMS干预可以阻止海马神经元受损,使细胞形态饱满,尼氏小体数目增多.（3）免疫组织化学结果显示：应激导致大鼠海马CA3区Bax蛋白表达显著增高（P＜0.01）,rTMS干预可以显著降低Bax蛋白表达（P＜0.01）.结论 rTMS干预可以改善慢性应激抑郁模型大鼠的抑郁行为及海马神经元的凋亡情况,可能与海马神经元凋亡蛋白Bax的表达下调有关.

Objective To explore the effects of repetitive transcranial magnetic stimulation on behaviors and hippocampus neuronal apoptosis in rats with chronic stress-induced depression.Methods 40 male SD rats of SPF grade were randomly divided into normol control group （n =8） and model preparation group （n =30） after screening.Rats in model preparation group were singly housed and given chronic unpredictable mild stress（CUMS） to build depression model.Excluding unsuccessful modeling rats,the model preparation group was divided into three groups：model group（n=8,without any treatment）,rTMS group （n=8,with the intervention of 10 Hz rTMS） and shame group （n=8,simulation of rTMS environment without rTMS stimulus）.The changes of behaviors in each group were detected by weight measurement,sucrose consumption test and open-field test.The changes of morphology of hippocampal neurons were detected by Nissl＇s staining.The changes of Bax in hippocampal neuron were detected by Immunohistochemical staining.Results （1） Behavioral results showed stress for 21 d could make rat behavior scores decrease significantly（all P〈0.05）,and rTMS intervention could significantly improve their behavior scores （all P〈0.01）.Compared with model group,the weight reduction rate （0.32±0.05）%,the score of sucrose consumption test（7.03 ± 1.02） and the score of open field test（8212.41 ± 1416.15,8.75 ± 1.58） in rTMS group was higher（P 〈0.01）.（2） Nissl staining showed stress for 21 d could make the number of hippocampal CA3 neurons was reduced,cell morphology was poor,and the number of Nissl bodies was reduced.rTMS intervention could increase the number of hippocampal CA3 neurons,cell morphology was integral and the number of Nissl bodies was increased.（3） Immunohistochemistry results showed stress for 21 d could cause the number of Bax cell were significantly increased（P〈0.01）,and rTMS intervention can make the number of Bax cell were significantly lower（P〈0.01）.Conclusion rTMS intervention improves the depressive behavior in chronic stress depression model rats and inhibits the apoptosis,which might work through inhibition of neuron apoptosis and decline of Bax expression in hippoeampal neurons.