| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2847042 | Respiratory Physiology & Neurobiology | 2014 | 8 Pages |
•Diaphragm tissue was harvested from Sprague-Dawley rats 1 or 7 days following cervical (C2) hemilesion (C2Hx).•Histological analysis demonstrated a reduction in cross-sectional area of all myofiber types in the ipsilateral diaphragm 1 day post-injury.•PCR analyses indicated increases of proteolytic and myogenic genes in the diaphragm.•An immediate myoplastic response occurs in the diaphragm after C2Hx with atrophy occurring within 1 day.
A cervical (C2) hemilesion (C2Hx), which disrupts ipsilateral bulbospinal inputs to the phrenic nucleus, was used to study diaphragm plasticity after acute spinal cord injury. We hypothesized that C2Hx would result in rapid atrophy of the ipsilateral hemidiaphragm and increases in mRNA expression of proteolytic biomarkers. Diaphragm tissue was harvested from male Sprague-Dawley rats at 1 or 7 days following C2Hx. Histological analysis demonstrated reduction in cross-sectional area (CSA) of type I and IIa fibers in the ipsilateral hemidiaphragm at 1 but not 7 days. Type IIb/x fibers, however, had reduced CSA at 1 and 7 days. A targeted gene array was used to screen mRNA changes for genes associated with skeletal muscle myopathy and myogenesis; this was followed by qRT-PCR validation. Changes in diaphragm gene expression suggested that profound myoplasticity is initiated immediately following C2Hx including activation of both proteolytic and myogenic pathways. We conclude that an immediate myoplastic response occurs in the diaphragm after C2Hx with atrophy occurring in ipsilateral myofibers within 1 day.
