下丘脑弓状核内GABA神经元与P物质神经元相互关系的免疫电镜双标研究

为了探讨下丘脑神经内分泌功能的突触调控机制和Ｐ物质（ＳＰ）神经元与γ－氨基丁酸（ＧＡＢＡ）神经元之间的相互关系，我们用包埋前免疫电镜ＰＡＰ双标技术，研究了大鼠弓状核内ＳＰ和ＧＡＢＡ神经元的超微结构分布。先以ＤＡＢ为呈色剂显示ＳＰ的免疫反应，然后用钢酸铵－ＴＭＢ法显示ＧＡＢＡ免疫反应，再经ＤＡＢ－氧化钴稳定后作免疫电镜研究。结果观察到，在弓状核内有大量含ＤＡＢ和ＴＭＢ免疫反应产物的神经元结构，ＤＡＢ反应产物为颗粒状或絮状沉淀，电子密度高，弥漫分布；ＴＭＢ反应产物呈针状或块状，散在分布。含ＤＡＢ免疫反应的结构有ＳＰ神经元的胞体、树突和轴突。含ＴＭＢ免疫反应的结构有ＧＡＢＡ神经元的胞体、树突和轴突。两种神经元均为中、小型细胞，在弓状核内混杂分布。含ＳＰ的轴突接受免疫反应阴性轴突的非对称性突触连接；含ＳＰ的树突与含ＧＡＢＡ的轴突形成对称性的轴一树突触。含ＧＡＢＡ的树突接受免疫反应用性轴突的非对称性突触连接，也接受含ＳＰ轴突的非对称性突触连接。本研究不仅在超微水平进一步证实了大鼠弓状核内存在着ＳＰ和ＧＡＢＡ神经元及其末梢，而且首次在形态学上为下丘脑氨基酸能神经元与肽能神经元之间的相互调控提供了超微结构依据。

DOUBLE IMMUNOELECTRON MICROSCOPIC LABELING STUDY OF THE RELATIONSHIP BETWEEN GABA-EKGIC ANO SP-ERGIC NEURONS IN THE HYPOTHALAMIC ARCUATE NUCLEUS

In order to explore the synaptic regulatory mechanism of hypothalamic neuroendocrine and the relationship between GABA-ergic and SP-ergic neurons,the ultrastructural distributions of(GABA-and SP-neurons in the arcuate nucleus were studied by means of pre-embedding double immunoelectron microscopic PAP labeling technique.First,SP immunoreactivity was demonstrated by using DAB as a chromogen,then,GABA-immunoreactivity was demonstrated by ammonium molybdate-TMB method. After being stabilized by DAB-cobalt chloride,the sections were processed for electron microscopic study.The results showed that in the arcuate nucleus there were a huge number of DAB and TMB reactive products-containing nervous structures,the SP appeared as high electron-dense granular or flocculent materials with diffuse distribution,whereas the GABA were dense needle or masslike deposits with dispersive pattern.Two kinds of immunoreactive products were located in the somata,dendrites and axons of SP-and GABA-like neurons respectively,SP-and GABA-like neurons both were small to medium in size and intermingled each other,The SP-containing axons received asymmetrical synapses from immunoreaction negative axons;the SP-containing dendrites formed symmetrical axodendritic synapses with GABA axons.The GABA-containing dendrites received asymmetrical synaptic contacts from negative axons or SP-containing axons.In present paper not only the SP-and GABA-neurons and their terminals existing in the arcuate nucleus were identified,but also provided the ultrastructural evidence of reciprocal regulations between amino acid-ergic and peptidergic neurons in the hypothalamus for the first time.