Atanasova Dimitrinka Y, Dimitrov Nikolay D, Lazarov Nikolai E
Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria; Department of Anatomy, Faculty of Medicine, Trakia University, Stara Zagora 6003, Bulgaria.
Department of Anatomy, Faculty of Medicine, Trakia University, Stara Zagora 6003, Bulgaria.
Acta Histochem. 2016 Oct;118(8):770-775. doi: 10.1016/j.acthis.2016.09.007. Epub 2016 Sep 28.
The carotid body (CB) is a major peripheral arterial chemoreceptor organ that evokes compensatory reflex responses so as to maintain gas homeostasis. It is dually innervated by sensory fibers from petrosal ganglion (PG) neurons, and autonomic fibers from postganglionic sympathetic neurons of the superior cervical ganglion (SCG) and parasympathetic vasomotor fibers of intrinsic ganglion cells in the CB. The presence of nitric oxide (NO), a putative gaseous neurotransmitter substance in a number of neuronal and non-neuronal structures, was examined in the CB, PG and SCG of the rat using nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry, nitric oxide synthase (NOS) immunohistochemistry and retrograde tracing. One week after injecting the retrograde tracer Fast Blue (FB) in the CB, we found that a subset of perikarya in the caudal portions of the PG and SCG were FB-labeled. Histochemistry and immunohistochemistry revealed that the majority of large- and medium-sized PG and SCG cells were NADPH-d positive and displayed a strong NOS immunostaining. We also observed that many varicose nerve fibers penetrating the CB and enveloping the glomus cells and blood vessels were NADPH-d reactive and expressed the constitutive isoforms of NOS, nNOS and eNOS. In addition, some autonomic microganglion cells embedded within, or located at the periphery of the CB, and not glomus or sustentacular cells were nNOS-immunopositive while CB microvasculature expressed eNOS. The present results suggest that NO is a transmitter in the autonomic nerve endings supplying the CB and is involved in efferent chemoreceptor inhibition by a dual mechanism.
颈动脉体（CB）是主要的外周动脉化学感受器器官，可引发代偿性反射反应以维持气体稳态。它由来自岩神经节（PG）神经元的感觉纤维以及来自颈上神经节（SCG）节后交感神经元的自主神经纤维和CB内固有神经节细胞的副交感舒血管纤维双重支配。利用烟酰胺腺嘌呤二核苷酸磷酸黄递酶（NADPH-d）组织化学、一氧化氮合酶（NOS）免疫组织化学和逆行追踪技术，在大鼠的CB、PG和SCG中检测了一氧化氮（NO）的存在，NO是许多神经元和非神经元结构中一种假定的气态神经递质物质。在CB中注射逆行示踪剂快蓝（FB）一周后，我们发现PG和SCG尾部的一部分核周体被FB标记。组织化学和免疫组织化学显示，大多数大中型PG和SCG细胞呈NADPH-d阳性，并显示出强烈的NOS免疫染色。我们还观察到，许多穿透CB并包裹球细胞和血管的曲张神经纤维呈NADPH-d反应性，并表达NOS的组成型同工型，即nNOS和eNOS。此外，一些嵌入CB内或位于CB周边的自主神经微神经节细胞而非球细胞或支持细胞呈nNOS免疫阳性，而CB微血管表达eNOS。目前的结果表明，NO是供应CB的自主神经末梢中的一种递质，并通过双重机制参与传出化学感受器抑制。
