Synaptic Inputs to Neurosecretory Neurons

为了在电镜水平上检测大鼠下丘脑神经分泌神经元的突触输入，在同一组织切片上使用了3h -去甲肾上腺素（^3H-NA）或5-羟多巴胺（5-OHDA）标记后，采用了双重免疫标记技术和免疫细胞化学与放射自显影相结合的技术。关于含神经垂体激素神经元的神经支配，在大鼠下丘脑室旁核和视上核（PVN、SON）中发现过氧化物酶-抗过氧化物酶（PAP）标记的酪氨酸羟化酶、GABA或5 -羟色胺免疫反应末端与胶体金标记的抗利尿激素或神经physin- ii免疫反应神经元突触接触。在PVN和SON中发现血清素或GABA免疫反应末端与催产素或神经physin I免疫反应神经元形成突触接触。这些发现表明含有抗利尿激素或催产素的神经元的分泌可能由儿茶酚胺能、氨基丁酸能或血清素能神经元通过突触调节。对于下丘脑含激素神经元的神经支配，发现选择性摄取^3H-NA或5-OHDA的儿茶酚胺末端与大鼠视前内侧区LHRH免疫反应神经元、PVN中CRH免疫反应启发和弓形核中GRH免疫反应神经元发生突触接触。这为儿茶酚胺能在下丘脑水平上控制LHRH、CRH或GRH的释放提供了形态学证据。此外，发现胶体金标记的TRH免疫反应终端与弓形核中papp -lebel的GEH免疫反应神经元发生突触接触。根据这一发现，含有trh的神经元可以通过大鼠下丘脑弓状核的突触支配GRH的分泌或具有一些其他功能。

To examine synaptic inputs to neurosecretory neurons in the rat hypothalamus at the electron microscopic level, some double immunolabeling techniques and a combined technique of immunocytochemistry and autoradiography after 3H-noradrenaline (^3H-NA) or 5-hydroxydopamine (5-OHDA) labeling in the same tissue section have been used. Concerning the innervation of neurohypophyseal hormone-containing neurons, peroxidase-antiperoxidase (PAP) labeled tyrosine hydroxylase, GABA or serotonin immunoreactive terminals making synaptic contacts with colloidal gold-labeled vasopressin or neurophysin-II immunoreactive neurons were found in the paraventricular and supraoptic nuclei (PVN, SON) of the rat hypothalamus. Serotonin or GABA immunoreactive terminals were found to make synaptic contacts with oxytocin or neurophysin I immunoreactive neurons in the PVN and SON. These findings suggest that the secretion of vasopressin- or oxytocin-containing neurons may be regulated via synapses by catecholaminergic, GABAergic or serotonergic neurons. As to the innervation of hypothalamic hormone-containing neurons, catecholamine terminals showing selective uptake of ^3H-NA or 5-OHDA were found to make synaptic contacts with LHRH immunoreactive neurons in the medial preoptic area, with CRH immunoreactive heurons in the PVN and with GRH immunoreactive neurons in the arcuate nucleus of the rat hypothalamus. These provide morphological evidences for catecholaminergic control of the release of LHRH, CRH or GRH, at the hypothalamic level. Furthermore, colloidal gold-labeled TRH immunoreative terminals were found to make synaptic contact with PAP-lebeled GEH immunoreactive neurons in the arcuate nucleus. From this finding, TRH-containing neurons may be considered to innervate GRH secretion or to have some other functions via synapses in the hypothalamic arcuate nucleus of the rat.