Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan.
Neuroscience. 2010 Apr 14;166(4):1068-82. doi: 10.1016/j.neuroscience.2010.01.041. Epub 2010 Jan 28.
The hypothalamo-neurohypophysial system (HNS) consisting of arginine vasopressin (AVP) and oxytocin (OXT) magnocellular neurons shows the structural plasticity including the rearrangement of synapses, dendrites, and neurovascular contacts during chronic physiological stimulation. In this study, we examined the remodeling of chondroitin sulfate proteoglycans (CSPGs), main extracellular matrix (ECM), in the HNS after salt loading known as a chronic stimulation to cause the structural plasticity. In the supraoptic nucleus (SON), confocal microscopic observation revealed that the immunoreactivity of 6B4 proteoglycans (PG) was observed mainly at AVP-positive magnocellular neurons but that of neurocan was seen chiefly at OXT-positive magnocellular neurons. The immunoreactivity of phosphacan and aggrecan was seen at both AVP- and OXT-positive magnocellular neurons. Electron microscopic observation further showed that the immunoreactivity of phosphacan and neurocan was observed at astrocytic processes to surround somata, dendrites, and terminals, but not synaptic junctions. In the neurohypophysis (NH), the immunoreactivity of phosphacan, 6B4 PGs, and neurocan was observed at AVP-positive magnocellular terminals, but the reactivity of Wisteria floribunda agglutinin lectin was seen at OXT-positive ones. The immunoreactivity of versican was found at microvessel and that of aggrecan was not detected in the NH. Quantitative morphometrical analysis showed that the chronic physiological stimulation by 7-day salt loading decreased the level of 6B4 PGs in the SON and the level of phosphacan, 6B4 PGs, and neurocan in the NH. These results suggest that the extracellular microenvironment of CSPGs is different between AVP and OXT magnocellular neurons and activity-dependent remodeling of CSPGs could be involved in the structural plasticity of the HNS.
下丘脑-神经垂体系统（HNS）由精氨酸加压素（AVP）和催产素（OXT）大细胞神经元组成，在慢性生理刺激下表现出包括突触、树突和神经血管接触的结构可塑性。在这项研究中，我们研究了在盐负荷后 HNS 中软骨素硫酸盐蛋白聚糖（CSPGs），主要细胞外基质（ECM）的重塑，盐负荷是一种引起结构可塑性的慢性刺激。在视上核（SON）中，共聚焦显微镜观察显示，6B4 蛋白聚糖（PG）的免疫反应性主要在 AVP 阳性大细胞神经元中观察到，但神经聚糖主要在 OXT 阳性大细胞神经元中观察到。神经胶蛋白和聚集蛋白聚糖的免疫反应性在 AVP 和 OXT 阳性大细胞神经元中均可见。电子显微镜观察进一步显示，磷酸聚糖和神经聚糖的免疫反应性在围绕体、树突和末端的星形胶质细胞突起中观察到，但不在突触连接处观察到。在神经垂体（NH）中，磷酸聚糖、6B4 PGs 和神经聚糖的免疫反应性在 AVP 阳性大细胞末端观察到，但 Wisteria floribunda 凝集素的反应性在 OXT 阳性末端观察到。在微血管中发现了 versican 的免疫反应性，而在 NH 中未检测到聚集蛋白聚糖的免疫反应性。定量形态计量学分析表明，7 天盐负荷的慢性生理刺激降低了 SON 中的 6B4 PGs 水平以及 NH 中的磷酸聚糖、6B4 PGs 和神经聚糖水平。这些结果表明，AVP 和 OXT 大细胞神经元之间的 CSPGs 细胞外微环境不同，CSPGs 的活性依赖性重塑可能参与了 HNS 的结构可塑性。
