Ginsberg S D, Hof P R, Young W G, Morrison J H
Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, New York 10029.
J Comp Neurol. 1994 Mar 22;341(4):476-91. doi: 10.1002/cne.903410405.
Previous reports on the rat and monkey hypothalamus have revealed a dense noradrenergic innervation within the hypothalamic paraventricular nucleus as assessed by dopamine-beta-hydroxylase immunohistochemistry. These single-label analyses were unable to delineate the cellular structures which receive this catecholaminergic innervation. Double-label preparations in the rat hypothalamic paraventricular nucleus have demonstrated synaptic interactions between noradrenergic varicosities and magnocellular neurons. However, the density and distribution of varicosities contacting chemically identified magnocellular neurons have not been assessed at the light or electron microscopic level. In this report, single-label immunohistochemistry was used to assess the morphology and distribution of vasopressin- and oxytocin-immunoreactive neurons within the macaque hypothalamic paraventricular nucleus. In addition, double-label immunohistochemistry was combined with confocal laser scanning microscopy to quantify the number of dopamine-beta-hydroxylase-immunoreactive varicosities in apposition to magnocellular neurons expressing vasopressin or oxytocin immunoreactivity. The morphology of chemically identified neurons was also compared to magnocellular neurons in the monkey hypothalamic paraventricular nucleus which were filled with Lucifer Yellow in order to assess the somatodendritic labeling of the immunohistochemical preparation. Qualitative assessment of immunohistochemically identified magnocellular cells indicated that vasopressin- and oxytocin-containing neurons are observed throughout the rostrocaudal extent of the monkey hypothalamic paraventricular nucleus, demarcating this structure from the surrounding anterior hypothalamus. The distribution of the two nonapeptides is complementary, with vasopressin-immunoreactive neurons having a greater somal volume and located in a more medial aspect of the mid and caudal hypothalamic paraventricular nucleus relative to oxytocin-immunoreactive perikarya. For the double-label preparations, a series of confocal optical sections was assessed through the total somal volume of vasopressin- and oxytocin-immunoreactive neurons along with the corresponding dopamine-beta-hydroxylase-immunoreactive varicosities in the same volume of tissue, generating a varicosity-to-neuron ratio which was further characterized morphologically to assess afferent input to the soma and proximal dendrites. Quantitative analysis revealed that vasopressin-immunoreactive neurons received approximately two thirds of their dopamine-beta-hydroxylase-immunoreactive varicosities in apposition to the proximal dendrites and one third in apposition to the somata. Furthermore, vasopressin-immunoreactive neurons received a greater innervation density than oxytocin-immunoreactive neurons, which did not have a differential distribution of varicosities on the proximal dendrites and somata. The distribution of dopamine-beta-hydroxylase-immunoreactive afferents on magnocellular neurons in the hypothalamic paraventricular nucleus may reflect a physiological role of this circuit in terms of preferential release of vasopressin from magnocellular neurons upon noradrenergic stimulation.
先前关于大鼠和猴下丘脑的报告显示，通过多巴胺-β-羟化酶免疫组织化学评估，下丘脑室旁核内有密集的去甲肾上腺素能神经支配。这些单标记分析无法描绘接受这种儿茶酚胺能神经支配的细胞结构。大鼠下丘脑室旁核的双标记制剂已证明去甲肾上腺素能曲张体与大细胞神经元之间的突触相互作用。然而，在光学或电子显微镜水平上，尚未评估与化学鉴定的大细胞神经元接触的曲张体的密度和分布。在本报告中，使用单标记免疫组织化学来评估猕猴下丘脑室旁核内血管加压素和催产素免疫反应性神经元的形态和分布。此外，将双标记免疫组织化学与共聚焦激光扫描显微镜相结合，以量化与表达血管加压素或催产素免疫反应性的大细胞神经元并列的多巴胺-β-羟化酶免疫反应性曲张体的数量。还将化学鉴定的神经元的形态与用路西法黄填充的猴下丘脑室旁核中的大细胞神经元进行了比较，以评估免疫组织化学制剂的体树突标记。对免疫组织化学鉴定的大细胞的定性评估表明，在猕猴下丘脑室旁核的整个 rostrocaudal 范围内观察到含有血管加压素和催产素的神经元，将该结构与周围的下丘脑前部区分开来。两种九肽的分布是互补的，血管加压素免疫反应性神经元的体细胞体积更大，并且相对于催产素免疫反应性核周体位于下丘脑室旁核中、尾部的更内侧。对于双标记制剂，通过血管加压素和催产素免疫反应性神经元的总体细胞体积以及相同体积组织中相应的多巴胺-β-羟化酶免疫反应性曲张体评估了一系列共聚焦光学切片，产生了曲张体与神经元的比率，并对其形态进行了进一步表征，以评估对体细胞和近端树突的传入输入。定量分析显示，血管加压素免疫反应性神经元约三分之二的多巴胺-β-羟化酶免疫反应性曲张体与近端树突并列，三分之一与体细胞并列。此外，血管加压素免疫反应性神经元比催产素免疫反应性神经元接受的神经支配密度更大，催产素免疫反应性神经元在近端树突和体细胞上没有曲张体的差异分布。下丘脑室旁核中大细胞神经元上多巴胺-β-羟化酶免疫反应性传入纤维的分布可能反映了该回路在去甲肾上腺素能刺激下大细胞神经元优先释放血管加压素方面的生理作用。
