Characterization of synapses in the rat subnucleus centralis of the nucleus tractus solitarius
Characterization of synapses in the rat subnucleus centralis of the nucleus tractus solitarius
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DOI：
10.1152/jn.00598.2014
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发表时间：
2015-01-15
影响因子：
2.5
通讯作者：
Travagli, R. Alberto
中科院分区：
文献类型：
--
作者：
Babic, Tanja;Ambler, Jason;Travagli, R. Alberto
孤束核（NTS）通过迷走神经A或C纤维接受丘脑下内脏感觉信息。我们最近表明，在对比心血管NTS内侧神经元，这响应于嘌呤或香草素激动剂，大多数食管NTS中央（cNTS）神经元响应香草素激动剂，而一个较小的子集响应香草素和嘌呤激动剂。本研究采用全细胞膜片钳技术、单细胞RT-PCR和免疫组织化学方法进一步研究cNTS神经元的神经化学和突触特性。刺激孤束可在cNTS诱发兴奋性突触后电流（EPSC），在64个神经元中，灌注嘌呤激动剂α β-亚甲基ATP（α β MeATP）可显著增加19个神经元诱发的EPSC幅度。此外，神经元与α β\MeATP反应性突触输入有不同的概率相比，非反应性神经元的释放。单细胞RT-PCR显示，13个α β MeATP反应神经元中有8个表达代谢型谷氨酸受体8（mGluR 8）mRNA，我们以前的研究表明，这是一个标记的谷氨酸能神经元，而只有3个表达谷氨酸脱羟酶，GABA能神经元的标记。α β MeATP-非反应性神经元表达mGluR 8的比例明显较低（30个神经元中有2个），而谷氨酸脱羟酶的表达比例较高（30个神经元中有12个）。食管扩张使cNTS中共定位的mGluR 8和c-Fos免疫反应神经元的数量从8.0 +/- 4%显著增加至20 +/-2.5%。这些数据表明，cNTS包括不同的神经元亚群，可以区分基于他们的嘌呤能激动剂的反应，这些亚群具有不同的神经化学和突触特征，这表明，从食管的感觉输入的整合依赖于迷走神经传入纤维和cNTS神经元之间的突触的离散组织。
The nucleus tractus solitarius (NTS) receives subdiaphragmatic visceral sensory information via vagal A- or C-fibers. We have recently shown that, in contrast to cardiovascular NTS medialis neurons, which respond to either purinergic or vanilloid agonists, the majority of esophageal NTS centralis (cNTS) neurons respond to vanilloid agonists, whereas a smaller subset responds to both vanilloid and purinerigic agonists. The present study aimed to further investigate the neurochemical and synaptic characteristics of cNTS neurons using whole cell patch-clamp, single cell RT-PCR and immunohistochemistry. Excitatory postsynaptic currents (EPSCs) were evoked in cNTS by tractus solitarius stimulation, and in 19 of 64 neurons perfusion with the purinergic agonist alpha beta-methylene ATP (alpha beta MeATP) increased the evoked EPSC amplitude significantly. Furthermore, neurons with alpha beta\MeATP-responsive synaptic inputs had different probabilities of release compared with nonresponsive neurons. Single cell RT-PCR revealed that 8 of 13 alpha beta MeATP-responsive neurons expressed metabotropic glutamate receptor 8 (mGluR8) mRNA, which our previous studies have suggested is a marker of glutamatergic neurons, whereas only 3 of 13 expressed glutamic acid dehydroxylase, a marker of GABAergic neurons. A significantly lower proportion of alpha beta MeATP-nonresponsive neurons expressed mGluR8 (2 of 30 neurons), whereas a greater proportion expressed glutamic acid dehydroxylase (12 of 30 neurons). Esophageal distension significantly increased the number of colocalized mGluR8-and c-Fos-immunoreactive neurons in the cNTS from 8.0 +/- 4% to 20 +/- 2.5%. These data indicate that cNTS comprises distinct neuronal subpopulations that can be distinguished based on their responses to purinergic agonists and that these subpopulations have distinct neurochemical and synaptic characteristics, suggesting that integration of sensory inputs from the esophagus relies on a discrete organization of synapses between vagal afferent fibers and cNTS neurons.