Stereotaxic Coordinates and Morphological Characterization of a Unique Nucleus (CSF-Contacting Nucleus) in Rat

Abstract

A unique nucleus, the cerebrospinal fluid (CSF)-contacting nucleus, has recently been recognized in the brain parenchyma. The outstanding feature of this nucleus is that the neural somas are located in the parenchyma, but their processes stretch into the CSF, implying that it may be a key structure bridging the nervous and body fluids-regulating systems and may play a pivotal role in modulating physiological activities. However, the true biological significance of this nucleus needs to be uncovered. The morphology of a nucleus is one of the most important parameters for neuroscience studies. For this reason, a common experimental animal, Sprague-Dawley (SD) rats, was chosen. The position, adjacent structures, neuronal distribution, size, three-dimensional reconstruction, and core coordinates of the CSF-contacting nucleus in SD rats of different weights (90–400 g) were illustrated for the first time. Furthermore, the formulas for calculating the core coordinates of the CSF-contacting nucleus in rats of different weights were revealed. Finally, the possible biological functions uncovered by past research are reviewed in this paper. This study provides an indispensable methodology and a significant reference for researchers interested in this unique nucleus.

Monosynaptic Input Mapping of Diencephalic Projections to the Cerebrospinal Fluid-Contacting Nucleus in the Rat

“…It is located within the ventral gray of the lower portion of the aqueduct (Aq) and upper portion of the fourth ventricle (4V) floor (Song et al, 2019). The outstanding feature of this nucleus is that the neural somata are located in the brain parenchyma but the processes stretch into the CSF (Song and Zhang, 2018;Song et al, 2019). The morphological connections of the CSF-contacting nucleus with non-CSF-contacting neurons, glia cells, and blood vessels have been confirmed with electron microscopy (Zhang et al, 2003).…”

“…), and heads were fixed on a stereotaxic instrument (Stoelting 51700, USA). A 1% CB solution (0.2 µl, Sigma, USA) was injected into the core of the CSF-contacting nucleus (Bregma: 8,242 ± 183 µm, Lateral: 92 ± 6 µm, Depth: 6,451 ± 109 µm; Song et al, 2019).…”

“…The cerebrospinal fluid (CSF)-contacting nucleus is a unique nucleus in the brain. It is located within the ventral gray of the lower portion of the aqueduct (Aq) and upper portion of the fourth ventricle (4V) floor (Song et al, 2019). The outstanding feature of this nucleus is that the neural somata are located in the brain parenchyma but the processes stretch into the CSF (Song and Zhang, 2018;Song et al, 2019).…”

“…It has been approximately 30 years now since we first discovered, named and began to study this nucleus. The basic biological characteristics of the CSF-contacting nucleus, such as its specific labeling method (Lu et al, 2008), location and morphology, stereotaxic coordinates (Song et al, 2019), substance distributions [neurotransmitter (Lu et al, 2011), receptor , ion channels (Wang et al, 2014)] and its relationship with some biological activities [such as pain , sodium appetite , stress , morphine dependence and withdrawal (Lu et al, 2011)] have been revealed. However, this nucleus is involved in pathways and mechanisms of different biological activities that are still to be clarified.…”

A special cranial nucleus (CSF-contacting nucleus) in primates

“…Based on their functions, these nuclei can be divided In the past 30 years [3], our studies revealed that after injecting peripheral nerve tracer CB-HRP into the rat ventricular system, the tracer is confined to the ventricular wall because of the existence of the brain barriers. The CB positive neuron cluster is always present at the ventral grey of the lower part of the aqueduct and the upper part of the fourth ventricle floor [3][4][5][6]. Only the neural processes that stretch into the CSF can be labelled.…”