中文摘要：

本研究采用荧光金（FG）逆行追踪与5-羟色胺（5-HT）免疫荧光组化染色相结合的双重技术观察了臂旁核（PBN）内5-HT阳性神经纤维和终末的来源。将FG注入PBN后，FG逆标神经元主要分布在三叉神经核簇、脑干网状结构外侧小细胞部、中缝核簇和中脑导水管周围灰质（PAG）；免疫荧光组化染色的结果显示5-HT阳性神经元主要位于中缝核簇和PAG；在中缝核簇和PAG内可见FG逆标并呈5-HT阳性的双重标记神经元。上述结果表明，中缝核簇和PAG内的5-HT能神经元向PBN发出投射，它们在躯体和内脏感觉信息的传递和调控方面发挥重要作用。

英文摘要：

Employing Fluoro-Gold （FG） retrograde tracing combined with immunofluoresence histochemical staining for serotonin （5-HT） double-labeling technique, we investigated the central origins of serotonin-immunopositive fibers and terminals in the parabrachial nucleus （PBN） of the rat. After injecting FG into the unilateral PBN, FG-labeled neuronal cell bodies were mainly observed in the trigeminal sensory nuclei, parvocellular part of the lateral reticular formation of the brainstem, raphe nuclei and midbrain periaqueductal gray （PAG）. The results of immunofluoresence histochemical staining revealed that 5-HT-immunopositive neuronal cell bodies were mainly found in the raphe nuclei and PAG. Within the raphe nuclei and PAG, some of the FG-labeled neuronal cell bodies were also shown 5-HT-immunopositive staining. The present results suggest that serotoninergic neurons in the raphe nuclei and PAG project to the PBN. These serotoninergic neurons might play important roles in the transmission, regulation and control on both soamtic and visceral information processing.