E. Broude et al., C-JUN EXPRESSION IN ADULT-RAT DORSAL-ROOT GANGLION NEURONS - DIFFERENTIAL RESPONSE AFTER CENTRAL OR PERIPHERAL AXOTOMY, Experimental neurology, 148(1), 1997, pp. 367-377
The response of the mature central nervous system (CNS) to injury diff
ers significantly from the response of the peripheral nervous system (
PNS). Axotomized PNS neurons generally regenerate following injury, wh
ile CNS neurons do not. The mechanisms that are responsible for these
differences are not completely known, but both intrinsic neuronal and
extrinsic environmental influences are likely to contribute to regener
ative success or failure. One intrinsic factor that may contribute to
successful axonal regeneration is the induction of specific genes in t
he injured neurons. In the present study, we have evaluated the hypoth
esis that expression of the immediate early gene c-jun is involved in
a successful regenerative response. We have compared c-Jun expression
in dorsal root ganglion (DRG) neurons following central or peripheral
axotomy. We prepared animals that received either a sciatic nerve (per
ipheral) lesion or a dorsal rhizotomy in combination with spinal cord
hemisection (central lesion). In a third group of animals, severed dor
sal roots were placed into the hemisection site along with a fetal spi
nal cord transplant. This intervention has been demonstrated to promot
e regrowth of severed axons and provides a model to examine DRG neuron
s during regenerative growth after central lesion. Our results indicat
ed that c-Jun was upregulated substantially in DRG neurons following a
peripheral axotomy, but following a central axotomy, only 18% of the
neurons expressed c-Jun. Following dorsal rhizotomy and transplantatio
n, however, c-Jun expression was upregulated dramatically; under those
experimental conditions, 63% of the DRG neurons were c-Jun-positive.
These data indicate that c-Jun expression may be related to successful
regenerative growth following both PNS and CNS lesions. (C) 1997 Acad
emic Press.