To investigate whether the CSF-contacting nucleus receives brainstem and spinal cord projections and to understand the functional significance of these connections.

The retrograde tracer cholera toxin B subunit (CB) was injected into the CSF-contacting nucleus in Sprague-Dawley rats according the previously reported stereotaxic coordinates. After 7–10 days, these rats were perfused and their brainstem and spinal cord were sliced (thickness, 40 μm) using a freezing microtome. All the sections were subjected to CB immunofluorescence staining. The distribution of CB-positive neuron in different brainstem and spinal cord areas was observed under fluorescence microscope.

The retrograde labeled CB-positive neurons were found in the midbrain, pons, medulla oblongata, and spinal cord. Four functional areas including one hundred and twelve sub-regions have projections to the CSF-contacting nucleus. However, the density of CB-positive neuron distribution ranged from sparse to dense.

Based on the connectivity patterns of the CSF-contacting nucleus receives anatomical inputs from the brainstem and spinal cord, we preliminarily conclude and summarize that the CSF-contacting nucleus participates in pain, visceral activity, sleep and arousal, emotion, and drug addiction. The present study firstly illustrates the broad projections of the CSF-contacting nucleus from the brainstem and spinal cord, which implies the complicated functions of the nucleus especially for the unique roles of coordination in neural and body fluids regulation.

调查CSF接触核是否接受脑干和脊髓投影，并了解这些连接的功能意义。

根据先前报道的立体定向坐标，将逆行示踪示踪霍乱毒素B亚基（CB）注入Sprague-Dawley大鼠的CSF接触核中。7-10天后，对这些大鼠进行灌注，并用冷冻切片机将其脑干和脊髓切成薄片（厚度为40μm）。所有切片均进行CB免疫荧光染色。荧光显微镜下观察CB阳性神经元在不同脑干和脊髓区域的分布。

逆行标记的CB阳性神经元存在于中脑，脑桥，延髓和脊髓中。包括112个子区域在内的四个功能区域都具有与CSF接触核的投影。但是，CB阳性神经元分布的密度从稀疏到密集。

基于CSF接触核的连接模式从脑干和脊髓接收解剖输入，我们初步得出结论并总结出CSF接触核参与疼痛，内脏活动，睡眠和唤醒，情绪以及药物成瘾。本研究首先说明了脑干和脊髓中CSF接触核的广泛预测，这暗示了核的复杂功能，特别是对于协调在神经和体液调节中的独特作用。