Journal of Neuroscience, Vol 8, 1739-1746, Copyright © 1988 by Society for Neuroscience
Neurofilament protein synthesis in DRG neurons decreases more after peripheral axotomy than after central axotomy
SG Greenberg and RJ Lasek
Bio-archtectonics Center, Case Western Reserve University Medical School, Cleveland, Ohio 44106.
Cytoskeletal protein synthesis was studied in DRG neurons after transecting
either their peripheral or their central branch axons. Specifically, the
axons were transected 5-10 mm from the lumbar-5 ganglion on one side of the
animal; the DRGs from the transected side and contralateral control side
were labeled with radiolabeled amino acids in vitro; radiolabeled proteins
were separated by 2-dimensional (2D) PAGE; and the amounts of radiolabel in
certain proteins of the experimental and control ganglia were quantified
and compared. We focused on the neurofilament proteins because they are
neuron-specific. If either the peripheral or central axons were cut, the
amounts of radiolabeled neurofilament protein synthesized by the DRG
neurons decreased between 1 and 10 d after transection. Neurofilament
protein labeling decreased more after transection of the peripheral axons
than after transection of the central axons. In contrast to axonal
transections, sham operations or heat shock did not decrease the
radiolabeling of the neurofilament proteins, and these procedures also
affected the labeling of actin, tubulin, and the heat-shock proteins
differently from transection. These results and others indicate that axonal
transection leads to specific changes in the synthesis of cytoskeletal
proteins of DRG neurons, and that these changes differ from those produced
by stress to the animal or ganglia. Studies of the changes in neurofilament
protein synthesis from 1 to 40 d after axonal transection indicate that the
amounts of radiolabeled neurofilament protein synthesis were decreased
during axonal elongation, but that they returned toward control levels when
the axons reached cells that stopped elongation.(ABSTRACT TRUNCATED AT 250
WORDS)