Karimnamazi Hamid, Travers Susan P, Travers Joseph B
Oral Biology, Ohio State University, Columbus, OH 43210, USA.
Brain Res. 2002 Dec 13;957(2):193-206. doi: 10.1016/s0006-8993(02)03438-8.
Projections to the parabrachial nucleus (PBN) from the nucleus of the solitary tract (NST) carry afferent signals from both the oral cavity and gastrointestinal tract. Although physiological studies suggest the convergence of oral and gastrointestinal sensory signals in the parabrachial nucleus, anatomical studies have emphasized the segregation of these pathways. To more precisely determine the anatomical relationship between gastric distension and oral afferent representation in PBN, small deposits of two anterograde tracers were made into the NST under physiological guidance in the same rat. Gastric terminations were dense and separate from taste projections in the rostral portion of the external lateral and dorsal lateral subnuclei. Gustatory projections were densest and separate from gastric terminations in the ventral lateral and central medial subnuclei of the caudal waist region, but were intermingled with gastric projections in these subnuclei and the external subnuclei at slightly more rostral levels. Patterns of segregation and overlap often appeared as 'patches' within or across subnuclear boundaries. In a second set of experiments, physiological evidence for overlap in PBN was evaluated from single unit extracellular responses evoked by gastric distension and orosensory (taste and orotactile) stimulation. Neurophysiological recordings verified that a small proportion of single cells within the waist and external subnuclei could be activated by both gastric and orotactile stimulation. The anatomical experiments further revealed intranuclear projections from the caudal NST injections that extended rostrally to sites at which responses to oral stimulation had been recorded. Although existing physiological data suggest such interactions are more limited than those in PBN, these anatomical data suggest that gastric/oral interactions may also exist in the NST.
孤束核（NST）向臂旁核（PBN）的投射携带来自口腔和胃肠道的传入信号。尽管生理学研究表明口腔和胃肠道感觉信号在臂旁核中会聚，但解剖学研究强调了这些通路的分离。为了更精确地确定胃扩张与PBN中口腔传入表征之间的解剖关系，在同一只大鼠的生理学引导下，将两种顺行示踪剂的小沉积物注入NST。胃终末在外侧和背外侧亚核的吻侧部分密集且与味觉投射分开。味觉投射在尾侧腰部区域的腹外侧和中央内侧亚核中最密集且与胃终末分开，但在这些亚核和稍靠前水平的外侧亚核中与胃投射混合。分离和重叠模式通常表现为亚核边界内或跨亚核边界的“斑块”。在第二组实验中，从胃扩张和口腔感觉（味觉和口腔触觉）刺激诱发的单细胞细胞外反应评估了PBN中重叠的生理学证据。神经生理学记录证实，腰部和外侧亚核内的一小部分单细胞可被胃和口腔触觉刺激激活。解剖学实验进一步揭示了来自尾侧NST注射的核内投射，其向吻侧延伸至记录到对口腔刺激反应的部位。尽管现有的生理学数据表明这种相互作用比PBN中的相互作用更有限，但这些解剖学数据表明胃/口腔相互作用也可能存在于NST中。
