Lasher R S, Lutz E M, Mulholland F, Sanderson R, Stewart J M, Bublitz C
Department of Cellular and Structural Biology, University of Colorado Medical School, Denver 80262.
Neurosci Lett. 1990 Sep 4;117(1-2):43-9. doi: 10.1016/0304-3940(90)90117-r.
Recently, it has been hypothesized that the N-terminal portion of substance P (SP), SP(1-7), which results from the action of endopeptidase 24.11 (EC3.4.24.11), could be involved in mediating the depressor effects of baroreceptor afferent activation via its action on cells in the nucleus tractus solitarius (NTS). In this study, the binding of a monoclonal antibody to endopeptidase 24.11 was examined immunohistochemically at the level of the caudal medulla of the rat brain. By light microscopy, intense immunoreactivity was seen in the NTS, in fibers bordering the area postrema, and in the area postrema itself. After electron microscopy, endopeptidase 24.11-like immunoreactivity was seen to be associated with the cytoskeleton and plasma membrane in axons, dendrites and glial processes. Antigen was also associated with synaptic vesicles and plasma membranes in presynaptic terminals forming mainly axo-dendritic synapses typical of vagal afferent terminals involved in the baroreceptor reflex. Thus, endopeptidase 24.11 appears to be localized at sites where it could effectively process SP prior to its binding to postsynaptic receptors.
最近，有人提出一种假说，即P物质（SP）的N端部分，即SP(1 - 7)，是内肽酶24.11（EC3.4.24.11）作用的产物，它可能通过作用于孤束核（NTS）中的细胞，参与介导压力感受器传入激活的降压作用。在本研究中，采用免疫组织化学方法在大鼠脑尾髓水平检测了单克隆抗体与内肽酶24.11的结合情况。通过光学显微镜观察，在孤束核、最后区边界的纤维以及最后区本身均可见强烈的免疫反应性。电子显微镜观察后发现，内肽酶24.11样免疫反应性与轴突、树突和神经胶质突起中的细胞骨架和质膜相关。抗原还与主要形成迷走神经传入终末典型的轴突 - 树突突触的突触前终末中的突触小泡和质膜相关，这些突触参与压力感受器反射。因此，内肽酶24.11似乎定位于其能在SP与突触后受体结合之前有效加工SP的部位。
