2023.02.27

Cerebrospinal fluid-contacting neuron tracing reveals structural and functional connectivity for locomotion in the mouse spinal cord

eLife. 2023;12:e83108. DOI: https://doi.org/10.7554/eLife.83108

Nakamura Y¹, Kurabe M², Matsumoto M^3,4, Sato T¹, Miyashita S¹, Hoshina K¹, Kamiya Y², Tainaka K¹, Matsuzawa H^5,6, Ohno N^7,8, Ueno M¹

¹Department of System Pathology for Neurological Disorders, Brain Research Institute, Niigata University
²Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences
³Section of Electron Microscopy, Supportive Center for Brain Research, National Institute
for Physiological Sciences
⁴Department of Developmental and Regenerative Neurobiology, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences
⁵Center for Advanced Medicine and Clinical Research, Kashiwaba Neurosurgical Hospital
⁶Center for Integrated Human Brain Science, Niigata University
⁷Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine
⁸Division of Ultrastructural Research, National Institute for Physiological Sciences

Abstract

Cerebrospinal fluid-contacting neurons (CSF-cNs) are enigmatic mechano- or chemo-sensory cells lying along the central canal of the spinal cord. Recent studies in zebrafish larvae and lampreys have shown that CSF-cNs control postures and movements via spinal connections. However, the structures, connectivity, and functions in mammals remain largely unknown. Here we developed a method to genetically target mouse CSF-cNs that highlighted structural connections and functions. We first found that intracerebroventricular injection of adeno-associated virus with a neuron-specific promoter and Pkd2l1-Cre mice specifically labeled CSF-cNs. Single-cell labeling of 71 CSF-cNs revealed rostral axon extensions of over 1800 μm in unmyelinated bundles in the ventral funiculus and terminated on CSF-cNs to form a recurrent circuitry, which was further determined by serial electron microscopy and electrophysiology. CSF-cNs were also found to connect with axial motor neurons and premotor interneurons around the central canal and within the axon bundles. Chemogenetic CSF-cNs inactivation reduced speed and step frequency during treadmill locomotion. Our data revealed the basic structures and connections of mouse CSF-cNs to control spinal motor circuits for proper locomotion. The versatile methods developed in this study will contribute to further understanding of CSF-cN functions in mammals.

*Reprinted under the terms of the Creative Commons Attribution License (CC BY).

Fig1.

Related BRI Department

System Pathology for Neurological Disorders - Ueno Lab
System Pathology for Neurological Disorders - Tainaka Lab