Corticospinal tract fibers cross the ephrin-B3-negative part of the midline of the spinal cord after brain injury
| Autor: | Masaki Ueno, Soichiro Mochio, Toshihide Yamashita, Shusaku Omoto |
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| Rok vydání: | 2011 |
| Předmět: |
Pyramidal Tracts
Biotin Ephrin-B3 Functional Laterality Mice Nerve Fibers Animals Medicine Ephrin B3 Protein Kinase C Analysis of Variance Pyramidal tracts business.industry General Neuroscience Receptor EphA4 Dextrans Recovery of Function General Medicine Anatomy Spinal cord Functional recovery Axonal sprouting Mice Inbred C57BL medicine.anatomical_structure Animals Newborn Spinal Cord Brain Injuries Corticospinal tract sense organs business human activities Locomotion Sprouting Motor cortex |
| Zdroj: | Neuroscience Research. 69:187-195 |
| ISSN: | 0168-0102 |
| DOI: | 10.1016/j.neures.2010.12.004 |
| Popis: | The fibers of corticospinal tract (CST), which control fine motor function, predominantly project to the contralateral spinal cord, not recross to the ipsilateral side. Ephrin-B3, which is expressed in the midline of the spinal cord, and its receptor, EphA4, are crucial for preventing CST fibers from recrossing the midline in the developing spinal cord. However, these fibers can cross the midline to the denervated side after a unilateral CST or cortical injury. We determined the reason CST fibers can cross the midline after a cortical injury and the changes in ephrin-B3-EphA4 signaling associated with such a crossing. We first examined axonal sprouting from CST fibers after unilateral ablation of the motor cortex in postnatal and adult mice. CST fibers crossed the midline of the spinal cord after cortical ablation, especially when conducted during the early postnatal period. These fibers were well associated with functional recovery after the injury. We next assessed the mRNA expression of ephrin-B3 and EphA4 before and after the ablation. Surprisingly, no changes were detected in the expression patterns. We found, however, that ephrin-B3 expression in the ventral part of the midline disappeared after postnatal day 9 (P9), but was pronounced along the entire midline before P6. Most of the CST fibers crossed the midline through the ventral region, where ephrin-B3 expression was absent. Our results suggest that ephrin-B3 is not expressed along the entire midline of the spinal cord, and sprouting axons can cross the midline at ephrin-B3-negative areas. |
| Databáze: | OpenAIRE |
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