Activation of NMDA receptors is necessary for fast information transfer at brainstem vagal motoneurons.
Activation of NMDA receptors is necessary for fast information transfer at brainstem vagal motoneurons.
复制标题
NMDA 受体的激活对于脑干迷走神经运动神经元的快速信息传递是必要的。
作者：
Y. T. Wang;D. Bieger;R. S. Neuman
在体和离体条件下研究了N-甲基-D-天冬氨酸（NMDA）兴奋性氨基酸亚型受体参与突触驱动的疑核运动神经元兴奋性反应。在麻醉大鼠中，局部应用毒蕈碱诱发虚构的食管扩张，同侧疑核内注射DL-2-amino-7-phosphonoheptanoic acid（DL-2-amino-7-phosphonoheptanoic acid，DL-2-amino-7-phosphonoheptanoic acid，DL-2-amino-7-phosphonoheptanoic acid，DL-7-phosphonoheptanoic acid，DL-2-amino-7-phosphonoheptanoic acid，DL-2-amino-7-phosphonoheptanoic acid，DL-7-phosphonoheptanoic acid）可可逆地阻断0.05- 0.5nmol（AP-7，0.5-1.5 nM）和（+-）-3-（2-羧基哌嗪-4-基）-丙基-1-膦酸（CPP; 0.5-1.5 nM）。在脑干矢状切片上，记录了疑核致密结构（AMBc）神经元的突触后电位。刺激假定的NTS传入引起一个复杂的兴奋性突触后电位（EPSP），它通常由高阈值快（HTF）和低阈值慢（LTS）成分。用AP-7（30-50 μ M）和CPP（50 μ M）的浴灌注选择性地阻断HTF而不影响LTS组分，而犬尿氨酸（1 mM）和6-氰基-7-硝基喹喔啉-2，3-二酮（CNQX，5-10 μ M）非选择性地抑制这两种组分。在足够的刺激强度下，EPSP产生由HTF分量引起的单个尖峰。AP-7（50 μ M）要么阻止了尖峰，要么增加了放电阈值。此外，在静息膜电位下，浴用NMDA诱导净内向电流（269 +/- 189 pA），其在-95至-35 mV范围内具有负斜率。总之，在生理条件下，NMDA受体参与孤隐突触传递和激活这些受体是必要的功能信息传递在这条途径。
The involvement of N-methyl-D-aspartate (NMDA) excitatory amino acid subtype receptors in synaptically driven excitatory responses of ambigual motoneurons was investigated in vivo and in vitro. In urethane-anaesthetized rats, fictive oesophageal peristalsis evoked by topical application of muscarine (0.05-0.5 nmol) to the dorsal surface of the solitarial complex (NTS) was reversibly blocked by ipsilateral intraambigual injection of DL-2-amino-7-phosphonoheptanoic acid (AP-7, 0.5-1.5 nM) and (+-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP; 0.5-1.5 nM). In brainstem sagittal slices, post-synaptic potentials were recorded from neurons of the compact formation of the nucleus ambiguus (AMBc). Stimulation of presumptive NTS afferents elicited a complex excitatory postsynaptic potential (EPSP) which usually consisted of both a high-threshold fast (HTF) and a low-threshold slow (LTS) component. Bath perfusion with AP-7 (30-50 microM) and CPP (50 microM) selectively blocked the HTF without affecting the LTS component, while kynurenate (1 mM) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5-10 microM) nonselectively suppressed both components. With sufficient stimulus strength, the EPSP generated a single spike arising from the HTF component. AP-7 (50 microM) either blocked the spike or increased the firing threshold. Furthermore, at the resting membrane potential, bath-applied NMDA induced a net inward current (269 +/- 189 pA) which had a negative slope in the range of -95 to -35 mV. In conclusion, NMDA receptors participate in solitario-ambigual synaptic transmission under physiological conditions and activation of these receptors is necessary for functional information transfer in this pathway.