Kummer W, Reinecke M, Heym C
Institute for Anatomy and Cell Biology, University of Heidelberg, F.R.G.
J Auton Nerv Syst. 1991 Aug;35(2):107-15. doi: 10.1016/0165-1838(91)90054-7.
This study was carried out to determine the ultrastructure and origin of previously described neurotensin-like immunoreactive (NT-LI) nerve fibres in the wall of the carotid sinus of the guinea pig. In our degeneration experiments, these NT-LI axons were unaffected by surgical sympathectomy but disappeared in response to transection of the carotid sinus nerve, thus suggesting a sensory origin. This assumption could be supported by combined retrograde tracing and immunohistochemistry. Primary afferent neurons of the sensory glossopharyngeal (petrosal) ganglion projecting to the carotid sinus were identified by injecting the retrograde fluorescent tracer, Fluoro-Gold, into the sinus wall, and some of these neurons displayed NT-LI. Within the carotid sinus, the terminals of these NT-LI sensory neurons exhibited ultrastructural features characteristic of baroreceptor endings, i.e. axonal swellings filled with mitochondria and closely associated to elastin. However, many endings also fulfilling the ultrastructural criteria for baroreceptors were devoid of immunolabelling. Thus, we conclude that the NT-LI terminals constitute a subgroup rather than the entire population of baroreceptor endings within the guinea pig carotid sinus. With respect to the established pharmacological effects of NT in guinea pig, we propose an involvement of NT-LI fibres in the modulation of baroreception at the peripheral level.
本研究旨在确定豚鼠颈静脉窦壁中先前描述的神经降压素样免疫反应性（NT-LI）神经纤维的超微结构和起源。在我们的变性实验中，这些NT-LI轴突不受手术交感神经切除术的影响，但在颈静脉窦神经横断后消失，因此提示其起源于感觉神经。这一假设可通过逆行追踪和免疫组织化学相结合得到支持。通过将逆行荧光示踪剂氟金注入窦壁，鉴定出投射至颈静脉窦的感觉舌咽（岩）神经节的初级传入神经元，其中一些神经元显示出NT-LI。在颈静脉窦内，这些NT-LI感觉神经元的终末表现出压力感受器末梢特有的超微结构特征，即充满线粒体并与弹性蛋白紧密相关的轴突肿胀。然而，许多也符合压力感受器超微结构标准的末梢却没有免疫标记。因此，我们得出结论，NT-LI终末构成豚鼠颈静脉窦内压力感受器末梢的一个亚群，而非全部。关于NT在豚鼠中已确定的药理作用，我们提出NT-LI纤维参与外周水平压力感受的调节。
