大鼠迷走神经初级传入纤维向孤束核投射的定位、定性研究

LOCALIZATION AND NEUROTRANSMITTER IDENTIFICATION OF THE PRIMARY AFFERENT FIBERS FROM THE VAGUS NERVE TO THE NUCLEUS TRACTUS SOLITARII OF THE RAT

为了探索迷走神经向孤束核(NTS)投射纤维的性质及分布特征,本文应用(1) 免疫细胞化学技术对NTS及结状神经节(NG)内ENK、SP、CGRP和VIP等四种活性物质的存在及分布进行了普查;(2) 用HRP跨越神经节追踪技术探索了迷走神经初级传入纤维在NTS内的投射定位;(3) 用HRP逆行标记技术和免疫细胞化学双重标记法结合切断实验印证了NG内神经元向NTS投射的纤维性质。结果证明:NST内含有此四种活性物质的阳性纤维和终末,主要分布于连合核及NTS内侧部,即相当于内侧亚核、中间亚核的区域。NTS中段的尾侧及尾段的吻侧阳性纤维和终末密度最高。此四种活性物质以SP样和L-ENK样阳性成分最为密集,VIP样次之,CGRP样密度最低。NG内亦存在含此四种活性物质的阳性神经元,其中L-ENK样阳性神经元是本文首次发现的,跨节追踪证明的迷走神经初级传入纤维向NTS的投射部位与这四种性质的纤维扣终末密集区大体上一致。逆行追踪与免疫细胞化学相结合的结果证明NG内存在此四种性质的双重标记细胞。切断一侧NG中枢端发现在术侧NTS内此四种活性物质的阳性纤维和终末的密集区都出现“脱落现象”,说明NG内含此四种活性物质的神经元都向NTS投射。

In order to reveal the neurotransmitter nature and distribution of the primary afferent fibers from the vagus nerve to the nucleus tractus solitarii (NTS), (1) immunocytochemical technique was used to survey L-ENK-, SP-, CGRP-, and VIP-like active substances in the NTS and vagal nodose ganglion (NG); (2) HRP transganglionic tracing method was carried out to study the distribution of the fibers of vagus nerve in the NTS; (3) HRP retrograde transport and PAP double labelling method combined with nodose ganglionectomy to detect nature of projecting fibers from the NG to the NTS. The results were as follows. There were positive immunoreactive fibers and terminals of the 4 substances mentioned above in the NG, distributed mainly in the commissural nucleus and medial part of the NTS (corresponding to the medial subnucleus and intermediate subnucleus). Both fibers and terminals, in caudal of middle segment and rostral of caudal segment of the NTS, were heavily stained. Among the 4, SP-and L-ENK-like stain were darkest, VIP-like next, and CGRP-like was the lightest. The immunoreactive positive neurons of the four substances could also be seen in the NG. Amog the four, L-ENK-like was not reported so far before. The projecting area of the vagus afferent fibers and the concentrated areas of fibers and terminals of the neuropeptides in the NTS were consistent with each other. The double-labeled cells in the NG were demonstrated by combined HRP transport and immunocytochemical technique, and the depletion of the 4 neuropeptides in the NTS after removal of the NG, indicated that NG neurons containing these 4 bioactive substances projected at the same time onto the NTS.