EVIDENCE FOR AFFERENT FIBER INNERVATION OF PARASYMPATHETIC NEURONS OF THE GUINEA-PIG CARDIAC GANGLION
EVIDENCE FOR AFFERENT FIBER INNERVATION OF PARASYMPATHETIC NEURONS OF THE GUINEA-PIG CARDIAC GANGLION
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DOI：
10.1016/0165-1838(94)00182-j
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发表时间：
1995-06-25
期刊：
影响因子：
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通讯作者：
PARSONS, RL
中科院分区：
文献类型：
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作者：
HARDWICK, JC;MAWE, GM;PARSONS, RL
本研究旨在确定肽能传入物质是否对豚鼠心脏神经节的副交感神经元具有调制作用。采用豚鼠心脏整体标本，用免疫组织化学方法对传入终末进行定位，并对单个神经元进行细胞内原位记录。细胞内电流注入和刺激神经节间纤维束均可诱发动作电位。根据放电特性，观察到两种类型的神经元，即时相神经元(95%)和强直神经元(5%)。高频(5~10 Hz)节间纤维刺激在许多细胞上产生钙依赖性的缓慢去极化，这不被100mM六甲铵或1mM阿托品所阻断。局部应用辣椒素(1 MM)可使传入神经末梢释放P物质和降钙素基因相关肽，从而延长去极化时间。哺乳动物速激肽P物质、神经激动素A和神经激动素B(均在100微米处)的微量喷射也产生了缓慢的去极化。速激肽受体亚型特异性激动剂的应用表明，这些神经元同时表达NK2和NK3受体。用神经生物素填充单个细胞以检查其形态，并对制备的细胞进行SP样免疫反应的反染色。结果表明，SP阳性纤维与时相神经元和紧张性神经元密切相关。根据这些结果，我们认为豚鼠心脏神经节的副交感神经元接受来自肽能传入纤维的输入，这种输入为心功能的潜在局部反射控制提供了一条途径。
The present study was done to establish whether peptidergic afferent inputs can modulate parasympathetic neurons of the guinea-pig cardiac ganglion. Whole mount preparations from the guinea-pig heart were utilized to localize afferent terminals by immunohistochemistry and for intracellular recordings from individual neurons in situ. Action potentials could be elicited by both intracellular current injection and stimulation of interganglionic fiber bundles. Two types of neuron, phasic (95%) and tonic (5%) as defined by their firing properties, were observed. High frequency (5-10 Hz) interganglionic fiber stimulation produced a calcium-dependent, slow depolarization in many cells which was not blocked by 100 mu M hexamethonium or 1 mu M atropine. A prolonged depolarization was also produced by local application of capsaicin (1 mM), which releases substance P and CGRP from afferent nerve terminals. Microejection of the mammalian tachykinins substance P, neurokinin A and neurokinin B (all at 100 mu M), also produced a slow depolarization. Application of specific agonists for the tachykinin receptor subtypes indicated that these neurons express both NK2 and NK3 receptors. Individual cells were filled with neurobiotin to examine their morphology and the preparations were counter-stained for SP-like immunoreactivity. The results demonstrated that SP-positive fibers are found in close apposition to both phasic and tonic neurons. From these results, we suggest that the parasympathetic neurons of the guinea-pig cardiac ganglion receive inputs from peptidergic, afferent fibers and that this input provides a pathway for potential local reflex control of cardiac function.