mTOR-自噬通路介导氯胺酮麻醉减轻抑郁症电休克治疗认知副反应的作用和机制研究

Electroconvulsive therapy (ECT) is the preferred treatment for treatment-resistant depression(TRD). However, the cognitive side effects of ECT affect the patient's early and long-term outcome of rehabilitation. Our study found that ketamine anesthesia can reduce the cognitive impairment of ECT. Its mechanism is still unknown. ECT enhances autophagy signaling in rat hippocampus. Autophagy reduces the activation of CREB, resulting in cognitive impairment. In the preliminary experiments, we found that ketamine downregulates the activation of autophagy caused by ECT. Ketamine rapidly activates the mammalian target of rapamycin (mTOR) , showing a dose-dependent manner. The activation of mTOR will downregulate the activation of autophagy. We hypothesize that ketamine may inhibit autophagy by activating the mTOR signaling pathway, then upregulat the CREB activity, with the result of reducing cognitive impairment. In order to determine the effective dose range of ketamine and elucidate its effect, we will use the electroconvulsive seizures to deal with the rat model of depression, and explore the effect of different doses of ketamine on autophagy, CREB activity and cognition by behavior test, electron microscopy and molecular biology experiments. In order to clarify the molecular mechanism of ketamine in regulating autophagy and protecting cognition , the activity of specific signal pathway, autophagy and CREB will be observed after specifically activating or blocking mTOR and upstream of PI3K / Akt and MEK / ERK pathway. This study will provide new idea and new direction for the prevention and treatment of cognitive impairment in ECT, and provide scientific basis for optimizing clinical treatment strategy.

电休克是难治性抑郁症的首选治疗方案，但其认知副反应影响患者早期、甚至远期康复。我们前期发现氯胺酮麻醉可减轻其认知损害，但机制未明。电休克激活海马自噬，而自噬下调CREB活性，损害认知。我们预实验发现氯胺酮有下调电休克自噬激活的作用。氯胺酮能快速激活mTOR，且与剂量有关，mTOR激活时自噬抑制。我们推测，氯胺酮可能通过激活mTOR抑制自噬、上调CREB活性，进而减轻认知损害。本项目拟通过电休克处理抑郁模型大鼠，结合行为学、电镜及分子生物学实验，研究不同剂量氯胺酮对海马自噬、CREB活性及认知的影响，确定氯胺酮有效保护认知的剂量范围，阐明其作用。并通过特异性激活或阻断mTOR及上游PI3K/Akt、MEK/ERK通路，观察相应信号通路、自噬、CREB活性变化，以明确氯胺酮调控自噬、保护认知的分子机制。本研究将为电休克认知损害的防治研究提供新的思路和切入点，并为优化临床治疗策略提供科学依据。

电休克治疗（ECT）是难治性抑郁症的首选治疗方式，但认知副反应明显。我们前期研究发现，氯胺酮麻醉可显著减轻ECT的认知副反应，本项目进一步探索了其可能的作用机制：通过建立抑郁症模型及电休克动物模型处理（ECS），研究了ECS对SD大鼠空间学习能力的影响，ECS的自噬激活作用，及氯胺酮异构体(2R,6R)-HNK对认知、自噬、CREB活性及相应信号通路的影响。结果显示：（1）ECS损害了大鼠的空间学习能力，且诱发了海马自噬，表现为ECS后大鼠的逃避潜伏期延长，自噬相关蛋白Beclin-1、LC3-II/LC3-I升高，自噬底物p62降低。（2）给与(2R,6R)-HNK处理后，逃避潜伏期降低，自噬激活减弱；给予自噬抑制剂3-MA后，p62水平较(2R,6R)-HNK处理时升高，且空间学习能力明显优于ECS组；给予自噬激活剂SMER28后，(2R,6R)-HNK的自噬抑制和认知保护作用被削弱。这提示，(2R,6R)-HNK通过抑制ECS诱导的自噬，使大鼠的空间学习能力改善。（3）(2R,6R)-HNK显著激活了mTOR，表现为p-mTOR表达上调。mTOR激活明显组，自噬水平明显低于ECS组，空间学习能力也优于ECS组。（4）抑制PI3K后，(2R,6R)-HNK的自噬抑制作用被削弱，p-mTOR水平显著降低。（5）ECS组的p-CREB水平显著低于sham组及(2R,6R)-HNK组。综合行为学、自噬研究、mTOR激活及相应信号通路的研究结果，本项目提示，ECS使自噬增强，抑制了CREB的活性，大鼠空间学习能力损害。氯胺酮异构体(2R,6R)-HNK通过PI3K/Akt/mTOR信号通路抑制自噬，上调CREB活性，减轻了ECS引起的认知损害。本项目初步阐明了氯胺酮麻醉对电休克治疗的认知保护作用机制，为该项技术的应用提供了更充分的科学证据。