EXCITATORY AMINO-ACID RECEPTOR-MEDIATED ACTIVATION OF SOLITARIAL DEGLUTITIVE LOCI
EXCITATORY AMINO-ACID RECEPTOR-MEDIATED ACTIVATION OF SOLITARIAL DEGLUTITIVE LOCI
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DOI：
10.1016/0028-3908(89)90190-1
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发表时间：
1989-09-01
影响因子：
4.7
通讯作者：
BIEGER, D
中科院分区：
文献类型：
--
作者：
HASHIM, MA;BIEGER, D
谷氨酸的吞咽作用进行了研究，以确定是否不同的兴奋性氨基酸受体介导激活模式发生器元件内的孤束核。当通过微量肺电泳应用时（0.01-10 pmol），来自多管玻璃微量移液器（尖端直径2-5 μ m），兴奋性氨基酸受体激动剂N-甲基-D，L-天冬氨酸（NMA）、N-甲基-D-天冬氨酸（NMDA）、使君子酸和红藻氨酸在腹侧亚核和中间亚核中的谷氨酸响应性咽部位显示出效力的等级顺序，其中KA > NMA/NMDA > QA;而在中央亚核内的食管部位，其作用强度顺序为NMA/NMDA > KA > QA。NMDA受体阻断剂2-氨基-5-膦酰基戊酸（APV）和2-氨基-7-膦酰基庚酸（AP 7）选择性地可逆性抑制谷氨酸诱发的食管反应，但对毒蕈碱诱发的节律性食管反应无相应影响。在孤束核的位点，谷氨酸引起了一个完整的吞咽序列，APV/AP 7幸免于咽部的组成部分，但选择性阻断食管的组成部分。非选择性谷氨酸受体拮抗剂，γ-D-谷氨酰甘氨酸抑制由谷氨酸引起的咽和食管反应。它的结论是，不同类型的兴奋性氨基和受体与吞咽运动前亚核的孤束核;红藻氨酸受体占主导地位的亚核腹侧和中间和NMDA受体的亚核中央。红藻氨酸和NMDA介导的机制都可以在生理条件下起作用。
The deglutitive actions of glutamate were investigated in urethane-anaesthetised rats in order to determine whether different excitatory amino acid receptors mediate activation of pattern generator elements contained within the nucleus tractus solitarii. When applied by micropneumophoresis (0.01-10 pmol) from multibarrelled glass micropipettes (tip diameter 2-5 .mu.m), the excitatory amino acid-receptor agonists, N-methyl-D, L-aspartate (NMA), N-methyl-D-aspartate (NMDA), quisqualate and kainate displayed a rank order of potency at glutamate-responsive pharyngeal sites, in the subnuclei ventralis and intermedialis, where KA > NMA/NMDA > QA; however, the potency followed the order NMA/NMDA > KA > QA at oesophageal sites within the subnucleus centralis. The NMDA-receptor blockers, 2-amino-5-phosphonovaleric acid (APV) and 2-amino-7-phosphonoheptanoic acid (AP7), selectively and reversibly inhibited the glutamate-evoked oesophageal responses, but had no corresponding effect on rhythmic oesophageal responses elicited by muscarine. At loci in the nucleus tractus solitarius, where glutamate elicited a complete swallowing sequence, APV/AP7 spared the pharyngeal component but selectivity blocked the oesophageal component. The nonselective glutamate-receptor antagonist, gamma-D-glutamylglycine suppressed both pharyngeal and oesophageal responses elicited by glutamate. It is concluded that different types of excitatory amino and receptors are associated with the deglutitive premotor subnuclei of the nucleus tractus solitarii; kainate receptors predominate within the subnuclei ventralis and intermedialis and NMDA receptors within the subnucleus centralis. Both kainate- and NMDA-mediated mechanisms can operate under physiological conditions.