Periaqueductal gray matter input to cardiac-related sympathetic premotor neurons
Periaqueductal gray matter input to cardiac-related sympathetic premotor neurons
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DOI：
10.1016/s0006-8993(98)00029-8
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发表时间：
1998-05-11
期刊：
影响因子：
2.9
通讯作者：
Loewy, AD
中科院分区：
文献类型：
--
作者：
Farkas, E;Jansen, ASP;Loewy, AD
中脑导水管周围灰质(PAG)是连接前脑情绪处理系统和防御反应运动通路的中脑纽带。这种反应的一部分依赖于调节心血管相关交感神经流出系统的FAG传出通路，包括那些调节心脏的通路。虽然已知FAG投射到迷走神经节前神经元，可能包括心脏迷走神经运动神经元，但关于FAG环路的信息可能影响交感神经介导的心功能，因此，本研究的目的是利用神经解剖学方法识别这些通路。首先，将伪狂犬病病毒(PRV)注入大鼠星状神经节，进行病毒跨神经元逆行示踪实验。存活4天后，5个FAG区含有跨突触感染神经元，包括背内侧、外侧和腹外侧的FAG柱以及Edinger-Westphal和连合前核。其次，用顺行轴突标记菜豆亮氨酸凝集素(PHA-L)对下行传出的FAG投射进行了研究，重点是确定FAG是否投射到中间外侧细胞柱(IML)。在整个胸段IML中几乎没有发现轴突标记，这表明PAG通过间接通路调节交感功能，其中突触传递通过交感运动前细胞群，尤其是延髓中的突触传递。这种可能性通过一项双重追踪研究进行了检验。先将PHA-L注入外侧或腹外侧核，6d后将伪狂犬病病毒注入同侧星状神经节。再存活4天后，用双重免疫组织化学方法显示PRV和PHA-L，以确定接受FAG输入的交感运动前区域。FAG支配下丘脑、脑笔和延髓中特定的交感前运动神经元，并在FAG内部提供相互的柱间联系(Jansen等人，Brain Res.784(1998)329-336)。主要通路终止于延髓腹侧，特别是位于中缝大核和巨细胞网状核的内侧区。这两个区域的5-羟色胺能和非5-羟色胺能交感前神经元都接受来自FAG的输入。在延髓头端腹外侧区(包括Cl肾上腺素能神经元)、蓝斑、A5细胞群、室旁核和下丘脑外侧核有弱的FAG向交感运动前神经元投射。综上所述，外侧和腹外侧柱似乎都能够通过一系列间接通路来调节心脏交感神经功能，这些间接通路涉及在下丘脑、中脑、脑桥和延髓的特定部位发现的交感前运动神经元，主要流出区终止于延髓吻侧腹内侧球脊区。(C)1998年爱思唯尔科学公司。
The periaqueductal gray matter (PAG) serves as the midbrain link between forebrain emotional processing systems and motor pathways used in the defense reaction. Part of this response depends upon FAG efferent pathways that modulate cardiovascular-related sympathetic outflow systems, including those that regulate the heart. While it is known that the FAG projects to vagal preganglionic neurons, including possibly cardiovagal motoneurons, no information exists on the FAG circuits that may affect sympathetically mediated cardiac functions and, thus, the purpose of this study was to use neuroanatomical methods to identify these pathways. First, viral transneuronal retrograde tracing experiments were performed in which pseudorabies virus (PRV) was injected into the stellate ganglion of rats. After 4 days survival, five FAG regions contained transynaptically infected neurons; these included the dorsomedial, lateral and ventrolateral FAG columns as well as the Edinger-Westphal and precommissural nuclei. Second, the descending efferent FAG projections were studied with the anterograde axonal marker Phaseolus vulgaris leuco-agglutinin (PHA-L) with a particular focus on determining whether the FAG projects to the intermediolateral cell column (IML). Almost no axonal labeling was found throughout the thoracic IML suggesting that the PAG modulates sympathetic functions by indirect pathways involving synaptic relays through sympathetic premotor cell groups, especially those found in the medulla oblongata. This possibility was examined by a double tracing study. PHA-L was first injected into either the lateral or ventrolateral FAG and after 6 days, PRV was injected into the ipsilateral stellate ganglion. After an additional 4 days survival, a double immunohistochemical procedure for co-visualization of PRV and PHA-L was used to identify the sympathetic premotor regions that receive an input from the FAG. The FAG innervated specific groups of sympathetic premotor neurons in the hypothalamus, pens, and medulla as well as providing reciprocal intercolumnar connections within the FAG itself (Jansen et al., Brain Res. 784 (1998) 329-336). The major route terminates in the ventral medulla, especially within the medial region which contains sympathetic premotor neurons lying within the raphe magnus and gigantocellular reticular nucleus, pars alpha. Both serotonegic and non-serotonergic sympathetic premotor neurons in these two regions receive inputs from the FAG. Weak FAG projections to sympathetic premotor neurons were found in the rostral ventrolateral medulla (including to Cl adrenergic neurons), locus coeruleus, A5 cell group, paraventricular and lateral hypothalamic nuclei. In summary, both the lateral and ventrolateral FAG columns appear to be capable of modulating cardiac sympathetic functions via a series of indirect pathways involving sympathetic premotor neurons found in selected sites in the hypothalamus, midbrain, pens, and medulla oblongata, with the major outflow terminating in bulbospinal regions of the rostral ventromedial medulla. (C) 1998 Elsevier Science B.V.