Neural Regeneration Research ›› 2026, Vol. 21 ›› Issue (5): 2040-2049.doi: 10.4103/NRR.NRR-D-24-00995

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Tracing motor neurons and primary sensory afferents of the monkey spinal cord with cholera toxin subunit B

Ziyu He1, 2, #, Zhixian Liu1, 2, #, Wenjie Xu1, 2, Ruoying Zhang1, 2, Shu Fan1, 2, Wei Wang1, 2, 3, *, Xiaolong Zheng1, 2, *   

  1. 1 Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China;  2 Hubei Key Laboratory of Neural Injury and Functional Reconstruction, Huazhong University of Science and Technology, Wuhan, Hubei Province, China;  3 Key Laboratory of Neurological Diseases of Chinese Ministry of Education, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
  • Online:2026-05-15 Published:2025-08-23
  • Contact: Wei Wang, PhD, MD, wwang@tjh.tjmu.edu.cn; Xiaolong Zheng, PhD, xl_zheng@hust.edu.cn.
  • Supported by:
    This work was supported by a grant from Ministry of Science and Technology China, No. 2022ZD0204704 (to WW); the National Natural Science Foundation of China, No. 82301572 (to XZ); and the China Postdoctoral Science Foundation, No. 2023M731202 (to XZ).

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Abstract: Nonhuman primates are increasingly being used as animal models in neuroscience research. However, efficient neuronal tracing techniques for labeling motor neurons and primary sensory afferents in the monkey spinal cord are lacking. Here, by injecting the cholera toxin B subunit into the sciatic nerve of a rhesus monkey, we successfully labeled the motor neurons and primary sensory afferents in the lumbar and sacralspinal cord. Labeled alpha motor neurons were located in lamina IX of the L6–S1 segments, which innervate both flexors and extensors. The labeled primary sensory afferents were mainly myelinated Aβ fibers that terminated mostly in laminae I and II of the L4–L7 segments. Together with the labeled proprioceptive afferents, the primary sensory afferents formed excitatory synapses with multiple types of spinal neurons. In summary, our methods successfully traced neuronal connections in the monkey spinal cord and can be used in spinal cord studies when nonhuman primates are used.

Key words: cholera toxin subunit B, interneuron, Macaca Mulatta, monkey, motor neuron, neuron tracing, primary sensory afferents, rhesus macaque, sciatic nerve, spinal cord