AUTHOR=Song Si-Yuan , Zhai Xiao-Meng , Dai Jia-Hao , Lu Lei-Lei , Shan Cheng-Jing , Hong Jia , Cao Jun-Li , Zhang Li-Cai 

TITLE=Novel Projections to the Cerebrospinal Fluid-Contacting Nucleus From the Subcortex and Limbic System in Rat

JOURNAL=Frontiers in Neuroanatomy

VOLUME=14

YEAR=2020

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2020.00057

DOI=10.3389/fnana.2020.00057

ISSN=1662-5129

ABSTRACT=<p><bold>Objective</bold>: To identify the novel projections received by the cerebrospinal fluid (CSF)-contacting nucleus from the subcortex and limbic system to understand the biological functions of the nucleus.</p><p><bold>Methods</bold>: The cholera toxin subunit B (CB), a retrograde tracer, was injected into the CSF-contacting nucleus in Sprague–Dawley rats. After 7–10 days, the surviving rats were perfused, and the whole brain and spinal cord were sliced for CB immunofluorescence detection. The CB-positive neurons in the subcortex and limbic system were observed under a fluorescence microscope, followed by 3D reconstructed with the imaris software.</p><p><bold>Results</bold>: CB-positive neurons were found in the basal forebrain, septum, periventricular organs, preoptic area, and amygdaloid structures. Five functional areas including 46 sub-regions sent projections to the CSF-contacting nucleus. However, the projections had different densities, ranging from sparse to moderate, to dense.</p><p><bold>Conclusions</bold>: According to the projections from the subcortex and limbic system, we hypothesize that the CSF-contacting nucleus participates in emotion, cognition, homeostasis regulation, visceral activity, pain, and addiction. In this study, we illustrate the novel projections from the subcortex and limbic system to the CSF-contacting nucleus, which underlies the diverse and complicated circuits of the nucleus in body regulations.</p>