http://stroke.ahajournals.org/content/44/7/1951.abstract
Abstract
Background and Purpose—We sought to demonstrate the contribution of axonal remodeling of the corticospinal tract (CST) in the spinal cord to functional
outcome after stroke.
Methods—Bilateral
pyramidotomy (BPT) or sham-BPT was performed in mice with transgenic
yellow fluorescent protein labeling in the
CST subjected to middle cerebral artery
occlusion (MCAo). Foot-fault and single pellet reaching tests were
performed 3 days
after MCAo and weekly thereafter. Mice were
euthanized at day 14 or 28 after stroke. Immunofluorescent staining for
growth-associated
protein-43 and Synaptophysin was performed on
cervical sections.
Results—Functional improvements were evident during the initial 14 days in both MCAo-sham-BPT and MCAo-BPT mice (P<0.01, versus day 3). Progressive recovery was present during the subsequent 14 days in MCAo-sham-BPT mice (P<0.001,
versus day 14) but not in MCAo-BPT mice. In the stroke-affected
cervical gray matter of MCAo-sham-BPT mice, growth-associated
protein-43-Cy3 staining on CST axons were
significantly increased at day 14 after stroke compared with normal mice
(P<0.001), and CST axonal density and Synaptophysin-Cy3
staining of CST-yellow fluorescent protein axonal terminals were
significantly
increased at day 28 compared with day 14
after MCAo (P<0.001).
Conclusions—Our
data demonstrate that voluntary motor recovery is associated with CST
axonal outgrowth and synaptic formation in the denervated
side of the spinal gray matter during the
later phase after stroke, suggesting that the CST axonal plasticity in
the spinal
cord contributes to neurological recovery.
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