tPA基因甲基化/去甲基化在丙泊酚保护抑郁大鼠电休克后学习记忆功能中的作用

Effects of tPA gene methylation/demethylation in Propofol protection of learning and memory function after electroshock therapy in depressive rats

目的探讨丙泊酚改善抑郁大鼠电休克治疗(ECT)后学习记忆功能的组织型纤溶酶原激活物(tPA)基因甲基化/去甲基化调控机制。方法成年雄性SD大鼠72只,随机取18只作为对照组(C组),剩余54只大鼠进行抑郁造模后随机分为D组、E组、F组,每组18只。C组不予实验处理;D组腹腔注射生理盐水+伪ECT;E组腹腔注射生理盐水+ECT;F组腹腔注射丙泊酚+ECT。采用糖水偏好百分比(SPP)、逃避潜伏期(EL)及空间探索时间(SET)检测大鼠抑郁行为及学习功能;逆转录PCR检测海马tPA、DNA甲基转移酶(DNMT)1、DNMT3a、DNMT3b及10~11易位(TET)1mRNA水平;Western blot检测海马tPA及DNMT1的表达;MeDIP-qPCR检测tPA甲基化率。结果ECT处理后,与D组比较,E、F组SPP上升,E组EL延长、SET缩短,海马CA1区tPA mRNA及蛋白表达下降,DNMT1 mRNA及蛋白表达增加,tPA甲基化率增加,差异有统计学意义(均P<0.05);与E组比较,F组EL缩短、SET延长,海马CA1区tPA mRNA及蛋白表达增加,DNMT1 mRNA及蛋白表达下降,tPA甲基化率降低(均P<0.05);各组DNMT3a、DNMT3b及TET1 mRNA的表达差异无统计学意义(均P>0.05)。结论丙泊酚能够有效减轻ECT诱导的学习记忆损伤,其机制可能与下调海马CA1区DNMT1表达减轻tPA的甲基化水平,增加tPA mRNA及蛋白表达水平有关。

Objective To investigate the protective effect of Propofol on learning and memory function in depressive rats after electroshock therapy(ECT)by regulating tissue plasminogen activator(tPA)gene methylation/demethylation.Methods Seventy-two adult male SD rats were used in this study and eighteen rats were randomly selected as the control group(group C).The remaining fifty-four rats were randomly divided into group D,group E and group F after depressive modeling,with 18 rats in each group.Group C was not given experimental treatment;group D was intraperitoneally injected with normal saline+pseudo-ECT;group E was intraperitoneally injected with normal saline+ECT;group F was intraperitoneally injected with Propofol+ECT.Depressive behavior and learning function of rats were measured by sucrose preference percentage(SPP),escape latency(EL)and space exploration time(SET).The mRNA levels of hippocampus tPA,DNA methyltransferase(DNMT)1,DNMT3a,DNMT3b and ten-elevan translocation(TET)1 were detected by reverse transcription PCR.The expressions of tPA and DNMT1 in hippocampus were detected by Western blot.MeDIP-qPCR was used to detect tPA methylation rate.After ECT treatment,compared with group D,SPP increased in Group E and F,EL prolonged and SET shortened in group E,tPA mRNA and protein expression in hippocampal CA1 area decreased,DNMT1 mRNA and protein expression increased,and tPA methylation rate increased,with statistically significant differences(all P<0.05).Compared with group E,in group F,EL shortened and SET prolonged,tPA mRNA and protein expression in hippocampal CA1 area increased,DNMT1 mRNA and protein expression decreased,and tPA methylation rate decreased(all P<0.05).There was no significant difference in mRNA expression of DNMT3a,DNMT3b and TET1 in each group(all P>0.05).Conclusion Propofol can effectively reduce ECT-induced learning and memory impairment in depressive rats.The mechanism may be related to the downregulate the expression of DNMT1 in the hippocampal CA1 region to reduce the methylation level of the tPA gene resulting in increase the expression level of tPA mRNA and protein.