5—HT能纤维向猫脊髓膈神经核及延髓膈肌前运动神经元的投射

实验在6只成年猫上进行,将WGA－HRP微量注入C5膈神经核内,通过逆行追踪及5－HT免疫组织化学FITC荧光双重标记方法,研究了中缝核5－HT能神经元向脊髓膈神经核的投射,同时观察了延髓膈肌产运动神经元接受5－HT能纤维投射的情况,结果在中缝苍白核观察到较多的HRP－5－HT双标记神经元,在中缝大核,中缝隐核观察到少数散在的双标记神经元,在延髓疑核,孤束核腹外侧区域的HRP单核记神经元（即膈肌前运动神经元）周围观察到5－HT能轴突末梢,结构表明：发自中缝苍白核5－HT能神经元的传出纤维可投射到脊髓膈神经核,延髓膈肌前运动神经元接受5－HT能纤维的传入投射。

Projections of 5-HTergic fibers to the spinal phrenic nucleus and medullary phrenic premotor neurons in the cat

Experiments were performed on 6 adult cats. Brainstem neurons that project to the phrenic nucleus were retrogradely labeled by microinjection of WGA HRP into the spinal phrenic nucleus The brainstem sections were double processed for HRP histochemical staining with TMB DAB method and 5 HT immunohistochemical staining with anti 5 HT primary antibody and FITC conjugated immunofluorescent secondary antibody. HRP 5 HT double labeled neurons were observed mainly in the nucleus raphe pallidus. A few double labeled neurons were also observed in nucleus raphe obscurus and nucleus raphe magnus. 5 HT immunopositive terminal fibers were observed in the vicinity of HRP single labeled neurons (phrenic premotor neurons) located in the nucleus ambiguus and ventrolateral solitary tract nucleus. The results indicate that the 5 HTergic neurons in the nucleus raphe pallidus send axonal projections to the phrenic nucleus, and that the brainstem phrenic premotor neurons also receive 5 HTergic axonal projections.