Gl. Li et al., INCREASED EXPRESSION OF GROWTH-ASSOCIATED PROTEIN-43 IMMUNOREACTIVITYIN AXONS FOLLOWING COMPRESSION TRAUMA TO RAT SPINAL-CORD, Acta Neuropathologica, 92(1), 1996, pp. 19-26
Growth-associated protein 43 (GAP43) is one compound used to indicate
growth of axonal endings during development and regeneration, particul
arly of peripheral neurons. Using immunohistochemistry, we have studie
d the expression of GAP43 in the spinal cord of rats subjected to mild
, moderate or severe compression injury and used neurofilament immunos
taining to demonstrate axonal injuries. Samples removed from the compr
essed T8-9, the cranial T7 and the caudal T10 segments were studied at
4 h, 24 h, 4 days and 9 days after injury. Control rats showed a mode
rate immunostaining of neurons in dorsal root ganglia, weak staining o
f ventral motor neurons and, with the exception of the corticospinal t
racts, a weak staining in some axons of the longitudinal tracts of the
cord. Injury in the compressed region led to increased GAP43 immunore
activity in axons of normal and expanded size. This occurred particula
rly 1-4 days after injury and normalized 9 days thereafter. More marke
d immunostaining was present in the cranial and caudal segments. The c
orticospinal tracts never showed such staining. The increase of GAP43
immunostaining is presumably caused by disturbed axonal transport from
neurons with the capacity to synthesize and transport the GAP43 antig
en. Transported material may thus be available for regeneration of axo
ns, but this source of material may vary between different classes of
axons within the cord.