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Motoneuron survival and axon regeneration following immediate versus delayed implantation of peripheral nerve graft into the spinal cord of adult rats with c5 and c6 root avulsion Tarazi, Christine

Abstract

Avulsion of spinal nerve roots is a CNS injury that results in motoneuron cell death and paralysis of the affected limb. It has been demonstrated in rats, cats and primates that following spinal nerve root avulsion injured motoneurons can extend axons into ventral roots or peripheral nerve (PN) grafts that have been immediately reimplanted into the spinal cord and result in functional reinnervation of denervated muscles. The effects of delayed PN graft implantation on motoneuron survival and axonal regeneration has not been studied in animals. Following avulsion of the left C5 and C6 ventral and dorsal roots in adult rats, the free end of a 3.5cm segment of common peroneal nerve was implanted into the ventrolateral area of the cord at C5 and C6. There were five groups of animals based on the time interval between root avulsion and PN graft implantation: immediate implantation, 1 week, 1 month, 2 months and 6 months. Two months after PN implantation, a fluorescent axonal tracer, Rhodamine-Dextran amine (RDA) was applied to the free end of the graft. Counts of RDA labeled neurons in the ipsilateral ventral horn were compared among the groups. Using the cell counts in the immediate implantation group (mean of 761 cells = 100%) as a reference for comparison, counts of RDA-labeled neurons was 82% at 1 week, 44% at 1 month and 38% at both 2 and 6 months. Counts were significantly lower in the 1, 2 and 6-month groups. To allow identification of C5 and C6 motoneurons, a separate group of experiments were done in which C5 and C6 motoneurons were labeled with another axonal tracer Fluorogold (FG) prior to avulsion, and PN grafts were implanted either immediately, 10 days or 1 month after root avulsion. Counts of FG, RDA or double-labeled neurons revealed that the % of ventral horn neurons that are G5 or C6 motoneurons are 31% (immediate), 33% (10 day) and 6% (1 month). A delay of 1 month in PN graft implantation resulted in a significant decrease in 1) the number of surviving C5 and C6 motoneurons; 2) the proportion of surviving C5 and C6 motoneurons that regenerated axons into the graft.

Item Metadata

Title
Motoneuron survival and axon regeneration following immediate versus delayed implantation of peripheral nerve graft into the spinal cord of adult rats with c5 and c6 root avulsion
Creator
Tarazi, Christine
Publisher
University of British Columbia
Date Issued
1998
Description
Avulsion of spinal nerve roots is a CNS injury that results in motoneuron cell death and paralysis of the affected limb. It has been demonstrated in rats, cats and primates that following spinal nerve root avulsion injured motoneurons can extend axons into ventral roots or peripheral nerve (PN) grafts that have been immediately reimplanted into the spinal cord and result in functional reinnervation of denervated muscles. The effects of delayed PN graft implantation on motoneuron survival and axonal regeneration has not been studied in animals. Following avulsion of the left C5 and C6 ventral and dorsal roots in adult rats, the free end of a 3.5cm segment of common peroneal nerve was implanted into the ventrolateral area of the cord at C5 and C6. There were five groups of animals based on the time interval between root avulsion and PN graft implantation: immediate implantation, 1 week, 1 month, 2 months and 6 months. Two months after PN implantation, a fluorescent axonal tracer, Rhodamine-Dextran amine (RDA) was applied to the free end of the graft. Counts of RDA labeled neurons in the ipsilateral ventral horn were compared among the groups. Using the cell counts in the immediate implantation group (mean of 761 cells = 100%) as a reference for comparison, counts of RDA-labeled neurons was 82% at 1 week, 44% at 1 month and 38% at both 2 and 6 months. Counts were significantly lower in the 1, 2 and 6-month groups. To allow identification of C5 and C6 motoneurons, a separate group of experiments were done in which C5 and C6 motoneurons were labeled with another axonal tracer Fluorogold (FG) prior to avulsion, and PN grafts were implanted either immediately, 10 days or 1 month after root avulsion. Counts of FG, RDA or double-labeled neurons revealed that the % of ventral horn neurons that are G5 or C6 motoneurons are 31% (immediate), 33% (10 day) and 6% (1 month). A delay of 1 month in PN graft implantation resulted in a significant decrease in 1) the number of surviving C5 and C6 motoneurons; 2) the proportion of surviving C5 and C6 motoneurons that regenerated axons into the graft.
Extent
5437755 bytes
Genre
Thesis/Dissertation
Type
Text
File Format
application/pdf
Language
eng
Date Available
2009-06-12
Provider
Vancouver : University of British Columbia Library
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
DOI
10.14288/1.0089136
URI
http://hdl.handle.net/2429/9051
Degree
Master of Science - MSc
Program
Zoology
Affiliation
Science, Faculty of; Zoology, Department of
Degree Grantor
University of British Columbia
Graduation Date
1999-05
Campus
UBCV
Scholarly Level
Graduate
Aggregated Source Repository
DSpace

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For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.