背景:丘脑系统在全身麻醉药诱导的可逆性无意识的调节中起着关键作用,尤其是全身麻醉(GA)的唤醒阶段。但是丘脑在GA引起的意识丧失(LOC)中的功能鲜为人知。丘脑网状核(TRN)是丘脑中唯一的GABA能神经元组成的核,它由表达小白蛋白(PV)和生长抑素(SST)的GABA能神经元组成。前段TRN(aTRN)表示参加麻醉诱导,但角色仍不清楚。本研究旨在揭示aTRN在异丙酚和异氟醚麻醉中的作用。
方法:我们首先设置c-Fos应变监测异丙酚和异氟醚麻醉期间aTRNPV和aTRNSST神经元的活性变化。随后,光遗传学工具用于激活aTRNPV和aTRNSST神经元,以阐明aTRNPV和aTRNSST神经元在异丙酚和异氟烷麻醉中的作用.记录并分析脑电图(EEG)记录和行为测试。最后,应用aTRNPV神经元的化学遗传激活来确认aTRN神经元在丙泊酚和异氟烷麻醉中的功能。
结果:c-Fos应变显示,在异丙酚和异氟醚麻醉的LOC期间,aTRNPV和aTRNSST神经元均被激活。光遗传学激活的aTRNPV和aTRNSST神经元促进异氟烷诱导并延迟丙泊酚和异氟烷麻醉后的意识恢复(ROC),同时,aTRNPV神经元的化学遗传激活表现出类似的作用。此外,在丙泊酚和异氟烷GA期间,aTRN神经元的光遗传学和化学遗传激活导致累积的爆发抑制率(BSR),尽管它们对EEG频率的功率分布表现出不同的影响。
结论:我们的发现表明,aTRNGABA能神经元在促进异丙酚和异氟烷介导的GA的诱导中起关键作用。
BACKGROUND: The thalamus system plays critical roles in the regulation of reversible unconsciousness induced by general anesthetics, especially the arousal stage of general anesthesia (GA). But the function of thalamus in GA-induced loss of consciousness (LOC) is little known. The thalamic reticular nucleus (TRN) is the only GABAergic neurons-composed nucleus in the thalamus, which is composed of
parvalbumin (PV) and somatostatin (SST)-expressing GABAergic neurons. The anterior sector of TRN (aTRN) is indicated to participate in the induction of anesthesia, but the roles remain unclear. This study aimed to reveal the role of the aTRN in propofol and isoflurane anesthesia.
METHODS: We first set up c-Fos straining to monitor the activity variation of aTRNPV and aTRNSST neurons during propofol and isoflurane anesthesia. Subsequently, optogenetic tools were utilized to activate aTRNPV and aTRNSST neurons to elucidate the roles of aTRNPV and aTRNSST neurons in propofol and isoflurane anesthesia. Electroencephalogram (EEG) recordings and behavioral tests were recorded and analyzed. Lastly, chemogenetic activation of the aTRNPV neurons was applied to confirm the function of the aTRN neurons in propofol and isoflurane anesthesia.
RESULTS: c-Fos straining showed that both aTRNPV and aTRNSST neurons are activated during the LOC period of propofol and isoflurane anesthesia. Optogenetic activation of aTRNPV and aTRNSST neurons promoted isoflurane induction and delayed the recovery of consciousness (ROC) after propofol and isoflurane anesthesia, meanwhile chemogenetic activation of the aTRNPV neurons displayed the similar effects. Moreover, optogenetic and chemogenetic activation of the aTRN neurons resulted in the accumulated burst suppression ratio (BSR) during propofol and isoflurane GA, although they represented different effects on the power distribution of EEG frequency.
CONCLUSIONS: Our findings reveal that the aTRN GABAergic neurons play a critical role in promoting the induction of propofol- and isoflurane-mediated GA.