Xiang Xuaner, Chen Yuzhang, Li Ke-Xin, Fang Jianqiao, Bickler Philip E, Guan Zhonghui, Zhou Wei
Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, United States.
Department of Physiology, University of California, San Francisco, San Francisco, CA, United States.
Front Cell Neurosci. 2022 Apr 26;16:891631. doi: 10.3389/fncel.2022.891631. eCollection 2022.
Hypothalamic orexin (hypocretin) neurons play crucial roles in arousal control. Their involvement in anesthesia and analgesia remains to be better understood. In order to enhance our view on the neuroanatomy, we systematically mapped the projections of orexin neurons with confocal microscope and light sheet microscope. We specifically expressed optogenetic opsins tagged with fluorescence markers in orexin neurons through adeno-associated viral infection in the mouse brain. The imaging results revealed fine details and novel features of the orexin projections throughout the brain, particularly related to the nuclei regulating arousal and pain. We then optogenetically activated orexin neurons in the lateral hypothalamus to study the effects on anesthesia-related behaviors. cFos staining showed that optogenetic stimulation can activate orexin neurons in the ChR2-mCherry group, but not the control mCherry group (62.86 ± 3.923% vs. 7.9 ± 2.072%; < 0.0001). In behavior assays, optogenetic stimulation in the ChR2-mCherry group consistently elicited robust arousal from light isoflurane anesthesia (9.429 ± 3.804 s vs. 238.2 ± 17.42 s; < 0.0001), shortened the emergence time after deep isoflurane anesthesia (109.5 ± 13.59 s vs. 213.8 ± 21.77 s; = 0.0023), and increased the paw withdrawal latency in a hotplate test (11.45 ± 1.185 s vs. 8.767 ± 0.7775; = 0.0317). The structural details of orexin fibers established the neuroanatomic basis for studying the role of orexin in anesthesia and analgesia.
下丘脑食欲素（下丘脑泌素）神经元在唤醒控制中起关键作用。它们在麻醉和镇痛中的作用仍有待进一步了解。为了加深我们对神经解剖学的认识，我们用共聚焦显微镜和光片显微镜系统地绘制了食欲素神经元的投射图。我们通过腺相关病毒感染小鼠大脑，在食欲素神经元中特异性表达带有荧光标记的光遗传学视蛋白。成像结果揭示了整个大脑中食欲素投射的精细细节和新特征，特别是与调节唤醒和疼痛的核团有关。然后，我们用光遗传学方法激活下丘脑外侧的食欲素神经元，以研究其对麻醉相关行为的影响。cFos染色显示，光遗传学刺激可激活ChR2-mCherry组的食欲素神经元，但对照组mCherry组未被激活（62.86±3.923%对7.9±2.072%；<0.0001）。在行为试验中，ChR2-mCherry组的光遗传学刺激始终能使小鼠从轻度异氟烷麻醉中强烈唤醒（9.429±3.804秒对238.2±17.42秒；<0.0001），缩短深度异氟烷麻醉后的苏醒时间（109.5±13.59秒对213.8±21.77秒；=0.0023），并增加热板试验中的爪部缩回潜伏期（11.45±1.185秒对8.767±0.7775；=0.0317）。食欲素纤维的结构细节为研究食欲素在麻醉和镇痛中的作用奠定了神经解剖学基础。
