Szigethy E M, Barnes K L, Diz D I
Department of Brain, Cleveland Clinic Foundation, OH 44195-5286.
Brain Res Bull. 1992 Dec;29(6):813-9. doi: 10.1016/0361-9230(92)90149-r.
Angiotensin II (Ang II) produces dose-related, site-specific cardiovascular effects in the canine and rat dorsal medulla. Our previous studies suggested that Ang II binding sites are associated with presynaptic vagal afferent fibers in the nucleus tractus solitarii (nTS) and vagal efferent neurons in the dorsal motor nucleus of the vagus (dmnX). High resolution autoradiography now establishes the relationship of putative Ang II receptors to the cytoarchitecture of these nuclei. Sections of the canine medulla oblongata were processed for film or emulsion autoradiography with 0.3-1 nM 125I-Ang II. Quantitative densitometry of films before and after processing sections for emulsion coating confirmed no selective alteration in labeling. In emulsion coated sections, dense labeling was seen over the majority of the large perikarya and surrounding neuropil in the ventral dmnX. Bands of label overlaid vagal efferent fibers coursing ventrolaterally to exit the medulla. In the nTS, Ang II binding was restricted to regions with heavy vagal afferent innervation. In the dorsal nTS, label was distributed over both cell bodies and neuropil, with highest density capping the solitary tract. In the medial nTS, label was concentrated over perikarya, with scattered grains over the intervening neuropil. The discrete subnuclear association of Ang II binding sites in the dorsal medulla with vagal cells and fibers documents that Ang II receptors are present on both afferent vagal fibers and intrinsic medullary neurons, and reveals an anatomical substrate for the autonomic effects of Ang II in this region.
血管紧张素II（Ang II）在犬类和大鼠延髓背侧产生剂量相关的、位点特异性的心血管效应。我们之前的研究表明，Ang II结合位点与孤束核（nTS）中的突触前迷走传入纤维以及迷走神经背运动核（dmnX）中的迷走传出神经元相关。高分辨率放射自显影现在确定了假定的Ang II受体与这些核的细胞结构之间的关系。用0.3 - 1 nM 125I - Ang II对犬延髓切片进行胶片或乳胶放射自显影处理。对用于乳胶包被的切片处理前后的胶片进行定量光密度测定，证实标记没有选择性改变。在乳胶包被的切片中，在腹侧dmnX的大多数大的核周体及其周围的神经毡上可见密集标记。标记带覆盖了向腹外侧走行以离开延髓的迷走传出纤维。在nTS中，Ang II结合局限于迷走传入神经支配密集的区域。在背侧nTS中，标记分布在细胞体和神经毡上，最高密度覆盖孤束。在内侧nTS中，标记集中在核周体上，在其间的神经毡上有散在的颗粒。延髓背侧Ang II结合位点与迷走细胞和纤维的离散亚核关联证明，Ang II受体存在于迷走传入纤维和延髓固有神经元上，并揭示了该区域Ang II自主效应的解剖学基础。
