Journal of Neuroscience, Vol 7, 4044-4053, Copyright © 1987 by Society for Neuroscience
Rapid axonal transport in focally demyelinated sciatic nerve
R Armstrong, AD Toews and P Morell
Biological Sciences Research Center, University of North Carolina, Chapel Hill 27514.
Focal demyelination was produced in rat sciatic nerve by unilateral
intraneural injection of anti-galactocerebroside serum. A functional lesion
was confirmed by the presence of nerve conduction block. Histologically,
this corresponded to demyelination of 50-70% of the fibers in nerve cross
sections; axonal structures appeared intact. At the time of maximal
demyelination (7 d), 35S-methionine or 3H-fucose was injected bilaterally
into the spinal cord ventral horn. At later times (5 hr-7 d), the sciatic
nerve was removed and radioactivity in successive nerve segments was
quantitated. The transport rates (approximately 260 mm/d) and the
composition of transported proteins and glycoproteins (separated on 7-15%
polyacrylamide gradient gels) were not altered in lesioned nerves relative
to contralateral control nerves. Light microscopic autoradiographic
analysis revealed a similar localization of axonally transported and
deposited glycoproteins in demyelinated and control fibers. Initially (8
hr), the majority of label was over axons. Labeled glycoproteins remaining
in the nerve after 1 week were retained mainly in axolemmal regions. We
conclude that acute focal primary demyelination does not lead to major
alterations in the transport or deposition of newly synthesized
macromolecules.