Davis B J, Kream R M
Department of Cell Biology, University of Alabama, Birmingham 35294.
Brain Res. 1993 Jul 9;616(1-2):6-16. doi: 10.1016/0006-8993(93)90185-p.
In several sensory systems, tachykinin- and opioid-expressing neurons functionally interact and influence the processing of afferent information. To determine whether a similar relationship exists for the processing of general and special (gustatory) visceral afferent information, the present study mapped the distributions of these two neuronal phenotypes within the nucleus of the solitary tract (NST) of the hamster by employing a combination of immuno- and in situ hybridization histochemistry (ISHH). The hamster was chosen because it is frequently used as a model in taste studies, yet there is a relative dearth of data about peptide expression or the classical neurotransmitters in the brainstem of this animal. The immunohistochemical analyses employed 2 highly selective antisera directed towards the prototypical tachykinin and opioid peptides, i.e. substance P (SP) and methionine enkephalin (ENK), respectively. Intense staining of fibers and preterminal/terminal puncta was concentrated in the rostral pole or gustatory zone of the NST. SP-, but not ENK-like immunoreactivity was also observed in long courses of axon bundles traversing the brainstem enroute to the NST. Local application of colchicine engendered the appearance of a moderate number of SP-positive somata that were mostly clustered in the medial, central and intermediate subnuclei, as well as being scattered throughout the remainder of the NST, including the gustatory zone. A low number of isolated ENK-positive somata were also observed throughout the NST. The somal areas of the SP- and ENK-positive somata averaged 86.3 and 81.8 microns 2, respectively. The ISHH studies were performed using 2 selective oligodeoxynucleotide probes with complementary sequences to mRNAs encoding gamma-preprotachykinin (PPT) and preproenkephalin (PPE) molecules. Overall, the cellular expression of PPT mRNA within the NST corresponded both in distribution and in number to those identified by immunohistochemical analyses using anti-SP serum. In contrast, ISHH analyses monitored a significantly greater number of PPE-expressing somata in the medial, central, intermediate and ventrolateral nuclei than were ENK immunoreactive. These findings indicate that tachykinin and opioid peptide phenotypes are represented in neurons throughout the hamster NST and suggest a functional role for PPT- and PPE-related peptide forms in the modulation of afferent general visceral and gustatory information.
在多个感觉系统中，表达速激肽和阿片样物质的神经元在功能上相互作用，并影响传入信息的处理。为了确定在一般和特殊（味觉）内脏传入信息的处理过程中是否存在类似的关系，本研究通过免疫组织化学和原位杂交组织化学（ISHH）相结合的方法，描绘了仓鼠孤束核（NST）内这两种神经元表型的分布。选择仓鼠是因为它经常被用作味觉研究的模型，但关于这种动物脑干中肽表达或经典神经递质的数据相对较少。免疫组织化学分析使用了2种高度选择性抗血清，分别针对典型的速激肽和阿片样肽，即P物质（SP）和甲硫氨酸脑啡肽（ENK）。纤维和终末前/终末小点的强烈染色集中在NST的吻端或味觉区。在穿过脑干通向NST的长轴突束中也观察到了SP样免疫反应，但未观察到ENK样免疫反应。局部应用秋水仙碱导致出现了中等数量的SP阳性胞体，这些胞体大多聚集在内侧、中央和中间亚核，也散布在NST的其余部分，包括味觉区。在整个NST中也观察到少量孤立的ENK阳性胞体。SP和ENK阳性胞体的胞体面积平均分别为86.3和81.8平方微米。ISHH研究使用了2种选择性寡脱氧核苷酸探针，其序列与编码γ-前速激肽原（PPT）和前脑啡肽原（PPE）分子的mRNA互补。总体而言，NST内PPT mRNA的细胞表达在分布和数量上与使用抗SP血清的免疫组织化学分析所鉴定的一致。相比之下，ISHH分析监测到在内侧、中央、中间和腹外侧核中表达PPE的胞体数量明显多于ENK免疫反应阳性的胞体。这些发现表明，速激肽和阿片样肽表型在整个仓鼠NST的神经元中均有体现，并提示与PPT和PPE相关的肽形式在调节传入的一般内脏和味觉信息中具有功能作用。
