Respiratory activity in brainstem of fetal mice lacking glutamate decarboxylase 65/67 and vesicular GABA transporter
Respiratory activity in brainstem of fetal mice lacking glutamate decarboxylase 65/67 and vesicular GABA transporter
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DOI：
10.1016/j.neuroscience.2007.02.050
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发表时间：
2007-05-25
期刊：
影响因子：
3.3
通讯作者：
Obata, K.
中科院分区：
文献类型：
--
作者：
Fujii, M.;Arata, A.;Obata, K.
哺乳动物延髓的呼吸神经网络在出生前表现出节律性活动。GABA和甘氨酸被认为参与呼吸节律的控制。最近，我们证实了谷氨酸脱羧酶（GAD） 67缺乏小鼠的呼吸衰竭[Tsunekawa N， Arata A, Obata K(2005)]。缺乏谷氨酸脱羧酶67的小鼠胎儿的自发口/舌运动和相关神经活动的发展及其抑制。[J].中国生物医学工程学报，21(2):391 - 391。为了进一步评估GABA和甘氨酸对胎儿呼吸功能的影响，我们研究了由GAD65-/-:67-/-和水泡GABA转运体(VGAT) -/-制备的脑干脊髓阻滞在胚胎第14 (E14)- e15和E18天小鼠的神经活动。在这些基因敲除小鼠中，GABA的合成和GABA和甘氨酸的囊泡释放分别完全缺失。在E18上，野生型小鼠在颈髓(C) 4水平的腹根观察到自发性呼吸放电，而基因敲除小鼠则没有。在GAD65-/-:67-/-制剂中，P物质可诱导C4放电，而在VGAT-/-制剂中则无。在E14-E15基因敲除小鼠中观察到C4放电，但频率低于野生型。使用“盲”膜片钳技术记录E18脑干呼吸网络中的神经元活动。在野生型胎儿中观察到呼气和吸气神经元具有其特有的放电模式。士的宁逆转了呼气神经元的吸气相超极化到大去极化。另一方面，基因敲除小鼠的同一区域的神经元自发地没有任何节奏地放电。P物质诱导GAD65-/-:67-/-小鼠髓质神经元的超极化电位。进一步给药士的宁诱导大的去极化电位。即使存在P物质和士的宁，VGAT-/-小鼠也未观察到节律活动。这些结果表明，GABA和甘氨酸的缺乏损害了小鼠胎儿呼吸网络的功能，并随着胎龄的增加而恶化。(c) 2007 IBRO。Elsevier Ltd.出版。版权所有。
The respiratory neural network in the mammalian medulla oblongata shows rhythmic activity before birth. GABA and glycine are considered to be involved in control of respiratory rhythm. Recently we have demonstrated respiratory failure in glutamic acid decarboxylase (GAD) 67-deficient mice [Tsunekawa N, Arata A, Obata K (2005) Development of spontaneous mouth/tongue movement and related neural activity, and their repression in mouse fetus lacking glutamate decarboxylase 67. Eur J Neurosci 21:173-178]. To further evaluate the involvement of GABA and glycine in fetal respiratory function, we studied neural activities in brainstem-spinal cord blocks prepared from GAD65-/-:67-/- and vesicular GABA transporter (VGAT) -/- mice on embryonic day 14 (E14)-E15 and E18. In these knockout mice, the synthesis of GABA and the vesicular release of GABA and glycine are completely absent, respectively. Spontaneous respiratory discharges were observed in the ventral roots at the cervical cord (C) 4 level from wild-type mice but not from the knockout mice on E18. Administration of substance P induced C4 discharges in GAD65-/-:67-/- preparations but not in VGAT-/- preparations. C4 discharges were observed in the knockout mice on E14-E15, although the frequency was lower than that in the wild-type. Neuronal activities in the respiratory network of the E18 brainstem were recorded using a "blind" patch-clamp technique. Expiratory and inspiratory neurons with their characteristic firing patterns were observed in the wild-type fetuses. Strychnine reversed inspiratory-phase hyperpolarization to large depolarization in expiratory neurons. On the other hand, neurons in the same area of the knockout mice fired spontaneously without any rhythm. Substance P induced hyperpolarizing potentials in medullary neurons of GAD65-/-:67-/- mice. Further administration of strychnine induced large depolarizing potentials. Rhythmic activities were not observed in VGAT-/- mice even in the presence of substance P and strychnine. These results indicate that the lack of GABA and glycine impairs the function of the respiratory network in mouse fetuses and the impairment progresses with fetal age. (c) 2007 IBRO. Published by Elsevier Ltd. All rights reserved.