正中隆起内NT能神经元的SP能神经支配的免疫电镜双标研究

应用包埋前免疫电镜PAP双标技术,对大鼠下丘脑正中隆起内的神经紧张素(neurotensin,NT)和P物质(substance P,SP)的分布进行了超微结构研究。先用DAB法显示SP免疫反应,然后用钼酸-TMB法显示NT免疫反应,再经DAB-氯化钴稳定后作免疫电镜包埋。电镜观察发现:在正中隆起内SP免疫反应呈电子密度高的颗粒状或絮状沉淀,广泛分布于轴突内的小清亮囊泡周围和基质内;NT免疫反应产物则为电子密度高的针状或块状,散在分布于胞体、树突和轴突内。含SP的轴突可接受免疫反应阴性轴突的传入性突触,也可与阴性树突形成传出性轴-树突触;含NT的树突和胞体均可接受阴性轴突的传入性突触。此外,SP阳性轴突末梢还可与NT阳性神经元的树突棘形成对称性轴-棘突触及与NT阳性轴突形成对称性轴-轴突触。实验结果表明:大鼠正中隆起内的NT能神经元接受SP能神经的支配,为下丘脑神经内分泌的突触调控提供了新的超微结构依据。

A DOUBLE LABELING IMMUNOELECTRON MICROSCOPIC STUDY OF THE SUBSTANCE P-ERGIC INNERVATION OF THE NEUROTENSINERGIC NEURONS IN THE MEDIAN EMINENCE

The distributions of neurotensin (NT) and substance P (SP) in the rat hypothalamic median eminence have been uhrastructurally studied by means of recently developed double labeling pre-embedding immunoelectron microscopic PAP technique. At first, the SP-immunoreaction was demonstrated by chromogen DAB, then the NT immunoreaction was demonstrated by molybdic acid-TMB method. After being stabilized by DABcobalt chloride, the sections were processed for electron microscopic embedding. Under electron microscope, it was observed that in the median eminence the SP-immunoreactire products appeared as highly electron-dense granular or flocculent materials deposited widely in the matrix of axoplasm and around the small clear synaptic vesicles; whereas the NT-immunoreactive products as highly electron-dense needle-like or massive feature distributed disspersively in the perikarya, dendrites and axonal terminals. The SP-containing axons might receive afferent synapses from immunoreaction-negative axons and formed efferent axodendritie synapses with negative dendrites. The NT-containing dendrites and perikarya might receive afferent synapses from immunoreaction-negatire axons. In addition, SP-positive axonal terminals established symmetric axospinous synapses with NT-positive dendritic spines, and axo-axonic synapses with NT-positive axons. The results of this study indicated that the NT-ergic neurons in the at median eminence received innervation from SP-ergic nerves, providing a new ultrastructural basis for the synaptic regulation of the neuroendocrine activities of the hypothalamus.