title: Plasticity of motor network and function in the absence of corticospinal projection.
abstract: Despite the obvious clinical interest, our understanding of how developmental mechanisms are redeployed during degeneration and regeneration after brain and spinal cord injuries remains quite rudimentary. In animal models of spinal cord injury, although spontaneous regeneration of descending axons is limited, compensation by intact corticospinal axons, descending tracts from the brainstem, and local intrinsic spinal networks all contribute to the recovery of motor function. Here, we investigated spontaneous motor compensation and plasticity that occur in the absence of corticospinal tract, using Celsr3|Emx1 mice in which the corticospinal tract is completely and specifically absent as a consequence of Celsr3 inactivation in the cortex. Mutant mice had no paresis, but displayed hyperactivity in open-field, and a reduction in skilled movements in food pellet manipulation tests. The number of spinal motoneurons was reduced and their terminal arbors at neuromuscular junctions were atrophic, which was reflected in electromyography deficits. Rubrospinal projections, calretinin-positive propriospinal projections, afferent innervation of motoneurons by calretinin-positive segmental interneurons, and terminal ramifications of monoaminergic projections were significantly increased. Contrary to control animals, mutants also developed a severe and persistent disability of forelimb use following the section of the rubrospinal tract at the C4 spinal level. These observations demonstrate for the first time that the congenital absence of the corticospinal tract induces spontaneous plasticity, both at the level of the motor spinal cord and in descending monoaminergic and rubrospinal projections. Such compensatory mechanisms could be recruited in case of brain or spinal cord lesion or degeneration.
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China.
authors: Qi
authors: Q
authors: Han
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China; Department of Human Anatomy, Medical School of Jinan University, Guangzhou 510632, PR China.
authors: Changshu
authors: C
authors: Cao
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China.
authors: Yuetong
authors: Y
authors: Ding
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China; Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China.
authors: Kwok-Fai
authors: KF
authors: So
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China; Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China.
authors: Wutian
authors: W
authors: Wu
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China. Electronic address: tquyibo@jnu.edu.cn.
authors: Yibo
authors: Y
authors: Qu
authors: Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou 510632, PR China; Department of Human Anatomy, Medical School of Jinan University, Guangzhou 510632, PR China; Co-innovation Center of Neuroregeneration, Nantong University, Jiangsu, PR China. Electronic address: tlibingzh@jnu.edu.cn.
authors: Libing
authors: L
authors: Zhou
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001927:Brain Diseases / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D015820:Cadherins / Q000172:deficiency / Q000235:genetics; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006948:Hyperkinesis / Q000235:genetics / Q000503:physiopathology; D008124:Locomotion / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000378:metabolism / Q000473:pathology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology*; D020511:Neuromuscular Junction Diseases / Q000235:genetics; D009473:Neuronal Plasticity / Q000235:genetics*; D011712:Pyramidal Tracts / Q000473:pathology*; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics; D020127:Recovery of Function / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism; D000099260:Empty Spiracles Homeobox Proteins
chemical_list: D000109:Acetylcholine; D015820:Cadherins; D002795:Choline O-Acetyltransferase; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D005680:gamma-Aminobutyric Acid; D000099260:Empty Spiracles Homeobox Proteins; C444454:Celsr3 protein, mouse
keywords: Celsr3; Corticospinal tract; Motor system; Propriospinal neurons; Rubrospinal tract