中文摘要：

位于新生和成年哺乳动物延髓腹外侧区的Pre-Bǒtzinger复合体（pre-Bǒtzingercomplex，PBC）被认为是呼吸节律产生中枢，神经激肽1受体（neurokinin-1 receptor，NKlR）是PBC神经元的主要标记物。5-羟色胺（5-hydroxytryptamine，5-HT或serotonin）作为一种重要的神经递质，可通过其受体调节呼吸中枢的节律性变化。本研究采用免疫荧光组织化学和免疫电镜双重标记技术，在激光共聚焦显微镜和电子显微镜下观察了大鼠PBC内5-HT样免疫阳性神经纤维与NKlR样免疫阳性神经元或NKlR免疫阴性神经元之间的关系，旨在为5-HT参与PBC神经元呼吸节律的产生和调控提供形态学依据。共聚焦显微镜结果显示：正常大鼠PBC内可观察到一定数量的5-HT样阳性纤维和终末，且有少量的阳性纤维和终末与PBC内NKlR样阳性神经元的胞体或树突形成密切接触。在电镜下可进一步观察到：5-HT样阳性纤维终末可与NKlR样阳性神经元的树突形成直接接触，但未观察到典型的突触联系。5-HT样阳性纤维终末可与NK1R免疫阴性的树突形成非对称性突触。本实验结果提示：5-HT可能通过旁分泌的方式或通过中间神经元间接调节PBC内NKlR样阳性神经元的活动，以实现对中枢呼吸节律的调控。

英文摘要：

The pre-Bǒtzinger complex （PBC） , located at the ventrolateral medulla, is thought to be the kernel of respiratory rhythmogenesis in mammals. Neurokinin-1 receptor （ NK1 R） has been found to be the marker of the PBC neurons. 5-hydroxytryptamine （5-HT） or serotonin, as an important neurotransmitter, modulates respiratory frequency in the PBC via its receptors. The present study, using immunofluorescence histochemical and immuno - electronic double labeling, aimed to reveal the relationship between 5-HT immunoreactive （ir） nerve fibers and NK1R-ir neurons in the PBC of the adult rat, to provide the morphological basis of 5-HT in participation of respiratory rhythmogenesis and regulation. Under the confocal laser-scanning microseopo, a number of 5-HT-ir fibers and terminals could be found in the PBC. The close appositions between 5-HT-ir fibers and NK1R-ir somas or dendrites could also be detectable, even though much less in amount. Under the electron microscope, 5-HT-ir terminals made direct contacts with NK1R-ir dendrites in the PBC, but no synaptic contact between them was found. However, 5-HT-ir terminals could asymmetrically synapse with NK1R-ir negative dendrites. The present resalts suggest that 5-HT-ir nerve fibers may participate in respiratory rhythmogenesis and regulation through a paracrine effect or volume transmission in the adult rat. 5-HT nerve fibers may also have synaptically function on the interneurons, then turn back to work on PBC neurons.