Plasticity of peptidergic innervation in healing rabbit medial collateral ligament |
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| Authors: | Paul T. Salo Jasmine A. Beye Ruth A. Seerattan Catherine A. Leonard Tyler J. Ivie Robert C. Bray |
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| Affiliation: | McCaig Institute for Bone and Joint Health, Department of Surgery, University of Calgary, Calgary, Alta.
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| Abstract: | BackgroundDenervation substantially impairs healing of the medial collateral ligament (MCL). Because normal ligaments are sparsely innervated, we hypothesized that neuropeptide-containing neurons would sprout or proliferate after ligament transection, followed by later regression with healing, in a manner analogous to blood vessels.MethodsWe transected the right MCL in 9 mature female New Zealand white rabbits and killed 3 rabbits at 2, 6 or 14 weeks. Alternate sets of 12-mm serial sections of healing MCL scars were examined by fluorescent immunohistochemistry for substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY) and pan-neuronal marker PGP9.5.ResultsNormal MCLs had few peptidergic fibres located in the epiligament in a perivascular pattern. At 2 weeks, PGP9.5-, SP-and CGRP-positive fibres had increased in the epiligament adjacent to the injury. By 6 weeks, there were increases in CGRP-and PGP9.5-positive fibres in epiligament and scar, with similar but less marked increases in SP-positive fibres. At 14 weeks, there was notable regression of immunostained peptidergic nerve fibres in the scar.ConclusionThis experiment shows evidence for a remarkable plasticity of ligament innervation after injury, supporting the idea that neuronal factors play a fundamental role in wound healing. |
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