大鼠孤束核向丘脑腹后内侧核及下丘脑外侧区的直接投射——HRP法研究

DIRECT PROJECTION FROM THE NUCLEUS TRACTUS SOLITARII TO THE VENTRAL POSTEROMEDIAL NUCLEUS OF THE THALAMUS AND LATERAL AREA OF THE HYPOTHALAMUS

将30～50%HRP导入20例实验动物一侧的丘脑腹后内侧核和10例实验动物的一侧的下丘脑外侧区。标记细胞出现在双侧孤束核上、中、下三段,但以注射同侧多见,中、下段标记细胞出现数量较多,上段较少。标记细胞在孤束核各亚核的分布也不相同,在内侧亚核、连合亚核内较为密集。标记细胞以中、小型为主,偶见大型,多为梭形,亦可见多角形,标记细胞有1-2个突起且可见分叉;标记细胞直径为15～25μm,本文证实了孤束核的中、下段向丘脑腹后内侧核及下丘脑外侧区存在着直接的上行投射,并推测该投射可能是传导一般内脏感觉(包括内脏痛)的上行通路之一。本文还结合文献对体壁传入与内脏传入神经元在孤束核以上的高位中枢内的汇聚及其意义进行了讨论。

The projections of the nncleus tractus solitarii(NTS)to the ventral posteromedial nucleus of thalamus(VPM)and lateral area of the hypothalamus(LHA)in rat were investigated with retrograde transport of horseradish peroxidase(HRP). 0.01-0.05 μl solutions of HRP(30-50%, Sigma Ⅵ)in saline were injected selectively into VPM and LHA of anesthetized albino rats of both sexes ranging from 280g to 350g in weight through a glass micropipete(tip inner diameter 40-50 μm). All sections were reacted with tetramethylbenzidine(TMB)according to the method of Mesulam. The retrograde labeled neurons were examined microscopically under bright field and dark field illumination. The results are presented as follows.Most of the labeled neurons were seen in ipsilateral medial subnuclei of NTS, intermediate segment, when HRP was injected into VPM, especially the medial parts of VPM. Most of the labeled neurons were seen in ipsilateral commissuraI nuclei of caudal segment and medial subnuclei of intermediate segment of NTS when HRP was injected into LHA, The results mentioned above provide direct anatomic evidence that the medial and commissural nuclei known as cardiovascular and gastrointestinal in teroceptive part of NTS, project to VPM and LHA. It is suggested that these pro jections be considered as a part of arelatively direct ascending pathway by which general visceral sensory information including visceral pain may be conveyed to the higher center, and as important morphologic basis for somato-visceral corelation theory.