Cervical dorsal rhizotomy (CDR) enlarges phrenic motoneurons in rats

W. Z. Zhan, P. Zhan, Y. S. Prakash, R. Kinkead, K. Smithson, G. S. Mitchell, G. C. Sieck

Research output: Contribution to journalArticlepeer-review


We hypothesized that CDR (C3-C5) would alter the morphology of phrenic motoneurons, reflecting spinal plasticity. Adult male rats were studied 28 days after CDR (N=6) or sham surgery (N=6). Phrenic motoneurons were labeled by intramuscular injection of cholera toxin B-fragment (CTB) three days before the rats were sacrificed. CTB labeled phrenic motoneurons were visualized using an immunohistochemical reaction with a Cy-3 conjugated secondary antibody. Longitudinal sections were imaged using a Bio Rad MRC500 confocal microscope. A series of optical slices (0.6 mm) through the phrenic motoneuron pool were digitized and transferred to a Sun workstation where optical slices were spatially reconstructed using ANALYZE software. Cell volumes and surface areas for ̃80 motoneurons were measured and corrected for the estimated Z-axis distortion, based on 3-D reconstruction of fluorescent microspheres of known diameter. CDR increased cell volumes and surface areas of the motoneurons in comparison to sham-operated rats. These structural adaptations suggest that the intrinsic excitability of phrenic motoneurons may decrease following CDR; however, this hypothesis remains to be tested directly.

Original languageEnglish (US)
Pages (from-to)A206
JournalFASEB Journal
Issue number3
StatePublished - Dec 1 1997

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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