光遗传激活蓝斑去甲肾上腺素能神经元对异氟醚麻醉小鼠的促醒作用

Promoting effect of optogenetic activation of norepinephrine neurons in locus coeruleus on induction of arousal in mice anesthetized with isoflurane

目的探讨光遗传激活蓝斑(LC)去甲肾上腺素能神经元对异氟醚麻醉小鼠诱导觉醒的促进作用。方法将12只雄性酪氨酸羟化酶(TH)-Cre小鼠随机分为观察组和对照组,每组6只,分别在立体定位仪下于LC脑区注射兴奋性光遗传病毒(AAV-EF1a-DIO-ChR2-mCherry)、空病毒(AAV-EF1a-DIO-mCherry)进行去甲肾上腺素能神经元刺激,并在LC脑区埋置光纤,颅骨放置三个脑电极。两组均给予蓝光刺激及1.4%异氟醚麻醉,记录麻醉诱导时间、麻醉觉醒时间。两组小鼠休息1周后,再次给予蓝光刺激及1.4%异氟醚麻醉,记录蓝光刺激前及刺激后5 min的脑电图,比较其爆发性抑制比率(BSR)。结果两组麻醉诱导时间比较无统计学差异(P>0.05),观察组麻醉觉醒时间短于对照组(P<0.05)。观察组蓝光刺激5 min BSR低于同组蓝光刺激前及对照组蓝光刺激后5 min(P均<0.05),对照组蓝光刺激前及刺激后5 min BSR比较无统计学差异(P>0.05)。结论光遗传激活LC去甲肾上腺素能神经元不会影响小鼠异氟醚麻醉的诱导时间,但会缩短其异氟醚麻醉的觉醒时间并降低脑电图BSR,从而促进异氟醚麻醉小鼠觉醒。

Objective To investigate the promoting effect of optogenetic activation of norepinephrine(NE)neurons in locus coeruleus(LC)on induction of arousal in mice anesthetized with isoflurane.Methods Twelve male TH-Cre mice were randomly dived into two groups:the observation group and control group,with 6 in each.Excitatory optogenetic virus(AAV-EF1a-DIO-ChR2-mCherry)and blank vector(AAV-EF1a-DIO-mCherry)were injected into the LC of mice under stereotaxic apparatus,then the optic fiber was implanted in the LC,and three electrodes were embedded in the skull.Mice in both groups were given blue light stimulation and 1.4%isoflurane anesthesia,we recorded the induction time and arousal time of anesthesia.After one week of rest,mice were anesthetized by 1.4%isoflurane and were given blue light stimulation for the second time,and we recorded the EEG before blue light stimulation and 5 min after stimulation,and compare the burst suppression ratio(BSR).Results There was no significant difference in induction time between the two groups(P>0.05),but the arousal time from anesthesia in the observation group was significant shorter than that of the control group(P<0.05).After 5 min of blue light stimulation in the observation group,the BSR was lower than that before blue light stimulation in the same group and that at 5 min after blue light stimulation in the control group;the control group showed no significant change in BSR at 5 min after blue light stimulation(P>0.05).Conclusion Optogenetic activation of NE neurons in the LC had no effect on the induction time of isoflurane anesthesia,but significantly shortened the arousal time and reduced the BSR in EEG,and thus promoted the awakening in mice anesthetized with isoflurane.