氯胺酮对抑郁大鼠海马微小RNA 206表达的影响

Effect of ketamine on expression of hippocampal microRNA-206 in mentally depressed rats

目的评价氯胺酮对抑郁大鼠海马微小RNA206（miR-206）表达的影响。方法清洁级健康雌性SD大鼠80只，体重200～300g，2～3月龄，采用随机数字表法，将其分为4组（／t=20）：正常对照组（c组）、氯胺酮组（K组）、抑郁组（D组）和抑郁＋氯胺酮组（D＋K组）。采用慢性不可预见轻度应激法制备大鼠抑郁模型。于模型制备成功后1d时，K组和D＋K组腹腔注射氯胺酮15mg／kg，其它2组给予等容量生理盐水。每组取10只大鼠，于模型制备前、模型制备7、14、21、28、35d、给药后1、3、5和7d时行糖水偏好实验，于给药后1d时行旷场实验，于给药后2d时行强迫游泳实验。每组于给药后6h时取5只大鼠，采用实时定量PCR法检测海马miR-206表达；每组于给药后2d时取5只大鼠，采用Western blot法检测海马脑源性神经营养因子（BDNF）表达。结果与C组比较，D组模型制备21～35d、给药后各时点蔗糖摄入量和旷场实验评分降低，强迫游泳不动时间缩短，海马miR，206表达上调，海马BDNF表达下调，K组强迫游泳不动时间缩短，海马miR-206表达下调，海马BDNF表达上调，D＋K组模型制备21—35d时蔗糖摄入量和旷场实验评分降低（P〈0．05）；与D组比较，D＋K组给药后各时点蔗糖摄入量升高，强迫游泳不动时间缩短，海马miR-206表达下调，海马BDNF表达上调（P〈0．05）。结论氯胺酮对大鼠发挥抗抑郁作用的机制与下调海马miR-206表达，上调海马BDNF表达有关。

Objective To evaluate the effect of ketamine on the expression of hippocampal microR- NA-206 （miR-206） in the mentally depressed rats. Methods Eighty healthy female Sprague-Dawley rats, weighing 200-300 g, aged 2-3 months, were randomly divided into 4 groups （n=20 each） using a random number table： normal control group （ C group） , ketamine group （ K group） , depression group （D group ） and depression ＋ ketamine group （D＋K group）. Mental depression was induced by exposing the animal to chronic unpredictable mild stress. At 1 day after successful establishment of the model, ketamine 15 mg/kg was injected intraperitoneally in K and D＋K groups, while the equal volume of normal saline was given in C and D groups. Before establishment of the model, at 7, 14, 21, 28 and 35 days after beginning of establishment of the model, and at 1, 3, 5 and 7 days after administration, sucrose preference test was performed. Open field test was carried out at 1 day after administration. Forced swimming test was performed at 2 days after administration. Five rats were sacrificed at 6 h after administration, and hippocampal tissues were isolated for determination of the expression of hippocampal miR-206 by quantitative real-time polymerase chain reaction. At 2 days after administration, 5 rats were sacrificed, and hippocampal brain-derived neurotrophic factor （BDNF） expression was detected by Western blot. Results Compared with C group, the volume of sucrose intake at 21-35 days after beginning of establishment of the model and at each time point after administration and the score of open field test were significantly decreased, the immobility time in forced swimming test was significantly prolonged, the expression of miR- 206 was up-regulated, and the expression of BDNF was down-regulated in D group, the immobility time in forced swimming test was shortened, the expression of miR-206 was down-regulated, and the expression of BDNF was up-regulated in group K, and the score of open field test and volume of sucrose intake at 21-35 days after beginning of establishment of the model and the score of open field test were significantly decreased in D＋K group （P〈0.05）. Compared with D group, the volume of sucrose intake at each time point after administration was significantly increased, the immobility time in forced swimming test was shortened, the expression of miR-206 was down-regulated, and the expression of BDNF was up-regulated in D＋K group （P〈 0.05）. Conclusion The mechanism by which ketamine exerts antidepressant effects is related to down-regulation of miR-206 expression and up-regulation of BDNF expression in the hippocampus of rats.