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Huang C, Wang S, Deng J, Gu X, Guo S, Yin X. A "messenger zone hypothesis" based on the visual three-dimensional spatial distribution of motoneurons innervating deep limb muscles. Neural Regen Res 2024; 19:1559-1567. [PMID: 38051900 PMCID: PMC10883482 DOI: 10.4103/1673-5374.387972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 09/04/2023] [Indexed: 12/07/2023] Open
Abstract
Abstract
JOURNAL/nrgr/04.03/01300535-202407000-00036/figure1/v/2023-11-20T171125Z/r/image-tiff
Coordinated contraction of skeletal muscles relies on selective connections between the muscles and multiple classes of the spinal motoneurons. However, current research on the spatial location of the spinal motoneurons innervating different muscles is limited. In this study, we investigated the spatial distribution and relative position of different motoneurons that control the deep muscles of the mouse hindlimbs, which were innervated by the obturator nerve, femoral nerve, inferior gluteal nerve, deep peroneal nerve, and tibial nerve. Locations were visualized by combining a multiplex retrograde tracking technique compatible with three-dimensional imaging of solvent-cleared organs (3DISCO) and 3-D imaging technology based on lightsheet fluorescence microscopy (LSFM). Additionally, we propose the hypothesis that “messenger zones” exist as interlaced areas between the motoneuron pools that dominate the synergistic or antagonist muscle groups. We hypothesize that these interlaced neurons may participate in muscle coordination as messenger neurons. Analysis revealed the precise mutual positional relationships among the many motoneurons that innervate different deep muscles of the mouse. Not only do these findings update and supplement our knowledge regarding the overall spatial layout of spinal motoneurons that control mouse limb muscles, but they also provide insights into the mechanisms through which muscle activity is coordinated and the architecture of motor circuits.
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Affiliation(s)
- Chen Huang
- MoE Key Laboratory for Trauma Treatment and Nerve Regeneration, Peking University, Beijing, China
- Department of Orthopedics and Trauma, Peking University People's Hospital, Beijing, China
| | - Shen Wang
- MoE Key Laboratory for Trauma Treatment and Nerve Regeneration, Peking University, Beijing, China
- Department of Orthopedics and Trauma, Peking University People's Hospital, Beijing, China
| | - Jin Deng
- MoE Key Laboratory for Trauma Treatment and Nerve Regeneration, Peking University, Beijing, China
- Department of Orthopedics and Trauma, Peking University People's Hospital, Beijing, China
| | - Xinyi Gu
- MoE Key Laboratory for Trauma Treatment and Nerve Regeneration, Peking University, Beijing, China
- Department of Orthopedics and Trauma, Peking University People's Hospital, Beijing, China
| | - Shuhang Guo
- MoE Key Laboratory for Trauma Treatment and Nerve Regeneration, Peking University, Beijing, China
- Department of Orthopedics and Trauma, Peking University People's Hospital, Beijing, China
| | - Xiaofeng Yin
- MoE Key Laboratory for Trauma Treatment and Nerve Regeneration, Peking University, Beijing, China
- Department of Orthopedics and Trauma, Peking University People's Hospital, Beijing, China
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Zhan YJ, Zhang SW, Zhu S, Jiang N. Tissue Clearing and Its Application in the Musculoskeletal System. ACS OMEGA 2023; 8:1739-1758. [PMID: 36687066 PMCID: PMC9850472 DOI: 10.1021/acsomega.2c05180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
The musculoskeletal system is an integral part of the human body. Currently, most skeletal muscle research is conducted through conventional histological sections due to technological limitations and the structure of skeletal muscles. For studying and observing bones and muscles, there is an urgent need for three-dimensional, objective imaging technologies. Optical tissue-clearing technologies seem to offer a novel and accessible approach to research of the musculoskeletal system. Using this approach, the components which cause refraction or prevent light from penetrating into the tissue are physically and chemically eliminated; then the liquid in the tissue is replaced with high-refractive-index chemicals. This innovative method, which allows three-dimensional reconstruction at the cellular and subcellular scale, significantly improves imaging depth and resolution. Nonetheless, this technology was not originally developed to image bones or muscles. When compared with brain and nerve organs which have attracted considerable attention in this field, the musculoskeletal system contains fewer lipids and has high levels of hemoglobin, collagen fibers, and inorganic hydroxyapatite crystals. Currently, three-dimensional imaging methods are widely used in the diagnosis and treatment of skeletal and muscular illnesses. In this regard, it is vitally important to review and evaluate the optical tissue-clearing technologies currently employed in the musculoskeletal system, so that researchers may make an informed decision. In the meantime, this study offers guidelines and recommendations for expanding the use of this technology in the musculoskeletal system.
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Affiliation(s)
- Yan-Jing Zhan
- State
Key Laboratory of Oral Diseases & National Clinical Research Center
for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Shi-Wen Zhang
- State
Key Laboratory of Oral Diseases & National Clinical Research Center
for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
- West
China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - SongSong Zhu
- State
Key Laboratory of Oral Diseases & National Clinical Research Center
for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
- West
China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Nan Jiang
- State
Key Laboratory of Oral Diseases & National Clinical Research Center
for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
- West
China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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Cui JJ, Wang J, Xu DS, Wu S, Guo YT, Su YX, Liu YH, Wang YQ, Jing XH, Bai WZ. Alexa Fluor 488-conjugated cholera toxin subunit B optimally labels neurons 3-7 days after injection into the rat gastrocnemius muscle. Neural Regen Res 2022; 17:2316-2320. [PMID: 35259856 PMCID: PMC9083145 DOI: 10.4103/1673-5374.337055] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Neural tract tracing is used to study neural pathways and evaluate neuronal regeneration following nerve injuries. However, it is not always clear which tracer should be used to yield optimal results. In this study, we examined the use of Alexa Fluor 488-conjugated cholera toxin subunit B (AF488-CTB). This was injected into the gastrocnemius muscle of rats, and it was found that motor, sensory, and sympathetic neurons were labeled in the spinal ventral horn, dorsal root ganglia, and sympathetic chain, respectively. Similar results were obtained when we injected AF594-CTB into the tibialis anterior muscle. The morphology and number of neurons were evaluated at different time points following the AF488-CTB injection. It was found that labeled motor and sensory neurons could be observed 12 hours post-injection. The intensity was found to increase over time, and the morphology appeared clear and complete 3-7 days post-injection, with clearly distinguishable motor neuron axons and dendrites. However, 14 days after the injection, the quality of the images decreased and the neurons appeared blurred and incomplete. Nissl and immunohistochemical staining showed that the AF488-CTB-labeled neurons retained normal neurochemical and morphological features, and the surrounding microglia were also found to be unaltered. Overall, these results imply that the cholera toxin subunit B, whether unconjugated or conjugated with Alexa Fluor, is effective for retrograde tracing in muscular tissues and that it would also be suitable for evaluating the regeneration or degeneration of injured nerves.
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Affiliation(s)
- Jing-Jing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jia Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Dong-Sheng Xu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Shuang Wu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ya-Ting Guo
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yu-Xin Su
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yi-Han Liu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yu-Qing Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xiang-Hong Jing
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wan-Zhu Bai
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
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Qi Z, Han S, Wang S, Gu X, Deng J, Huang C, Yin X. Visual three-dimensional spatial distribution of motor neurons innervating superficial limb muscles in mice. Front Cell Neurosci 2022; 16:904172. [PMID: 35936500 PMCID: PMC9354668 DOI: 10.3389/fncel.2022.904172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
The coordination of motor function in the spinal cord depends on selective connections between distinct classes of motor neurons and their target muscles. However, knowledge regarding the anatomical connections between the superficial limb skeletal muscles and the motor neurons that innervate them is limited. In this study, with a combination of the multiple retrograde tracing method with 3DISCO clearing, we explored the spatial distribution of different motor neuron pools targeting specific superficial muscles of the forelimbs or hindlimbs in mouse spinal cords, which were dominated by the radial, median, ulnar, or sciatic nerve. This study reveals the precise interrelationship among different motor neuron pools innervating limb muscles under the same space and time. The data will help to further understand the neural loop and muscular motor coordination.
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Affiliation(s)
- Zhidan Qi
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Shuai Han
- Department of Orthopaedics, Peking University Third Hospital, Beijing, China
| | - Shen Wang
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Xinyi Gu
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Jin Deng
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Chen Huang
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Xiaofeng Yin
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
- *Correspondence: Xiaofeng Yin,
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English AW, Carrasco D, Hoffman D, Isaacson R, Kang SS, Khan S, Liu X, Ye K. Oral Treatments With the TrkB Ligand Prodrug, R13, Promote Enhanced Axon Regeneration Following Peripheral Nerve Injury. Front Cell Neurosci 2022; 16:857664. [PMID: 35496909 PMCID: PMC9051483 DOI: 10.3389/fncel.2022.857664] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022] Open
Abstract
Axon regeneration after peripheral nerve injury is slow and inefficient, leading to generally poor functional recovery. Activity-dependent experimental therapies that increase expression of brain-derived neurotrophic factor (BDNF) and its TrkB receptors enhance regeneration, suggesting that treatments with BDNF might also be effective. However, recombinant human BDNF (rhBDNF), as well as 7,8-dihydroxyflavone (7,8-DHF), a small molecular BDNF mimetic, may have limited treatment applications because of their modest oral bioavailability and pharmacokinetic profile. R13 is a 7,8-DHF prodrug. Upon oral administration, it is converted in the liver to 7,8-DHF. In immunoblots from tissues at the site of nerve injury, a single oral treatment with R13 to mice following sciatic nerve transection and repair produced a rapid and prolonged increase in immunoreactivity to phosphorylated TrkB, prolonged phosphorylation of mitogen activated protein kinase (MAPK/Erk1/2), and a rapid but transient increase in phosphorylated AKT (protein kinase B). Intramuscular injections of fluorescent retrograde tracers into the gastrocnemius and tibialis anterior muscles 4 weeks after nerve injury resulted in significantly greater numbers of labeled motoneurons and dorsal root ganglion neurons in R13-treated mice than in vehicle-treated controls. Direct electromyographic (EMG) responses (M waves) were significantly larger in R13-treated mice 4 weeks after injury than vehicle-treated controls or mice treated with oral 7,8-DHF. Oral treatments with the prodrug, R13, are a potent therapy for stimulating axon regeneration and functional recovery after peripheral nerve injury.
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Affiliation(s)
- Arthur W. English
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
- Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA, United States
- *Correspondence: Arthur W. English,
| | - Dario Carrasco
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Dustin Hoffman
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Robin Isaacson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Seong Su Kang
- Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - Samia Khan
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, United States
| | - Xia Liu
- Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - Keqiang Ye
- Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, United States
- Faculty of Life and Health Sciences, Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
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