Onimaru Hiroshi, Ikeda Keiko
Department of Physiology, Showa University School of Medicine, Tokyo, Japan.
Clinical Research Department, National Hospital Organization Murayama Medical Center, Tokyo, Japan.
Adv Exp Med Biol. 2021;1293:449-458. doi: 10.1007/978-981-15-8763-4_29.
Using an optogenetic approach, we analyzed a local neuron network of the respiratory center in the medulla of a brainstem-spinal cord preparation isolated from neonatal rat. We developed a transgenic (Tg) rat line in which Phox2b-positive cells expressed archaerhodopsin-3 (Arch) or one of the step-function channelrhodopsin variants (ChRFR) under the control of Phox2b promoter-enhancer regions. Then, in en bloc preparations from 0- to 2-day-old Tg neonatal rats, we analyzed membrane potential changes of medullary respiratory-related neurons in response to photostimulation of the rostral ventral medulla. The photostimulation-induced inhibition or facilitation of the respiratory rhythm in Arch-expressing or ChRFR-expressing Tg rat preparations, respectively. Selective photoactivation of Phox2b-positive neurons expressing ChRFR in the rostral ventrolateral medulla of a neonatal rat en bloc preparation induced membrane potential changes of respiratory-related neurons that were dependent on heterogeneous properties of synaptic connections in the respiratory center. We concluded that the optogenetic approach is a powerful method of verifying a hypothetical model of local networks among respiratory-related neurons in the rostral ventrolateral medulla of neonatal rat.
我们采用光遗传学方法，分析了从新生大鼠分离的脑干脊髓标本延髓中呼吸中枢的局部神经元网络。我们培育了一种转基因（Tg）大鼠品系，其中Phox2b阳性细胞在Phox2b启动子增强子区域的控制下表达古紫质-3（Arch）或一种阶跃函数视紫红质变体（ChRFR）。然后，在0至2日龄Tg新生大鼠的整体标本中，我们分析了延髓呼吸相关神经元对延髓腹侧头端光刺激的膜电位变化。光刺激分别在表达Arch或ChRFR的Tg大鼠标本中诱导呼吸节律的抑制或促进。在新生大鼠整体标本的延髓腹外侧头端，对表达ChRFR的Phox2b阳性神经元进行选择性光激活，诱导了呼吸相关神经元的膜电位变化，这些变化取决于呼吸中枢中突触连接的异质性。我们得出结论，光遗传学方法是验证新生大鼠延髓腹外侧头端呼吸相关神经元之间局部网络假设模型的有力方法。
