模拟失重大鼠延髓内脏带向下丘脑室旁核投射的儿茶酚胺能神经元表达Fos

Fos expression of catecholaminergic neurons within medullary visceral zone projecting to hypothalamic paraventricular nucleus in simulated weightlessness rats

确定延髓内脏带向下丘脑室旁核 (PVN)投射通路是否参与对模拟失重的反应。用HRP逆行追踪结合抗Fos和抗酪氨酸羟化酶 (TH)的免疫组织化学三重标记技术 ,观察 4周模拟失重大鼠延髓内脏带向PVN投射的儿茶酚胺能神经元Fos表达情况。发现有 7种不同的标记细胞 :HRP ,Fos ,TH单标细胞 ;Fos/HRP ,Fos/TH ,HRP/TH双标细胞 ;Fos/HRP/TH三标细胞。主要分布于延髓内脏带即延髓中尾段的孤束核和腹外侧区以及两者之间的网状结构。向PVN投射的神经元中有 15.3%为Fos阳性细胞 ,即对失重起反应 ,而这些神经元中有 6 2 .6 %为儿茶酚胺能神经元。结果显示 。

Whether the projectional pathway from the medullary visceral zone (MVZ) to the paraventricular nucleus (PVN) of hypothalamus involved in the response to the weightlessness simulation was explored in our study. By using a triple labeling method combining HRP retrograde tracing with anti-Fos and -TH immunohistochemical staining, the distributions of Fos positive catecholaminergic neurons in the MVZ projecting to the PVN were observed in rats after weightlessness simulation for 4 weeks. Under light microscope, seven types of positively stained neurons could be distinguished within the MVZ, namely neurons single-labeled with Fos, HRP or TH, respectively; neurons double-labeled with Fos/TH, Fos/HRP or HRP/TH separately; and neurons triple-labeled with Fos, HRP and TH staining. These cells were mainly located in the MVZ——an arc zone including the nucleus of tractus solitarii, the ventrolateral medulla and the intermediate reticular zone. Fos positive neurons projecting to the PVN constituted 15.3% of the total population of HRP-labeled neurons and 62.6% of them were catecholaminergic neurons. The results suggested that the catecholaminergic projectional pathway from the MVZ to the PVN participated in the cardiovascular response under weightlessness.