IMPLANTATION OF PNS GRAFT INHIBITS THE INDUCTION OF NEURONAL NITRIC-OXIDE SYNTHASE AND ENHANCES THE SURVIVAL OF SPINAL MOTONEURONS FOLLOWING ROOT AVULSION
Wt. Wu et al., IMPLANTATION OF PNS GRAFT INHIBITS THE INDUCTION OF NEURONAL NITRIC-OXIDE SYNTHASE AND ENHANCES THE SURVIVAL OF SPINAL MOTONEURONS FOLLOWING ROOT AVULSION, Experimental neurology, 129(2), 1994, pp. 335-339
In a spinal root injury model, our previous studies have shown that in
duction of nitric oxide synthase (NOS) appears only in spinal motoneur
ons of the root-avulsed segment in which significant motoneuron loss o
ccurs but not in those of the distal root-axotomized segment (root axo
tomy 5-10 mm from the spinal cord) in which most motoneurons survive t
he injury. One hypothesis for the different response of motoneurons to
root avulsion and distal root axotomy is that neurotrophic factors pr
oduced by the remaining peripheral nervous system (PNS) component are
available for the distally axotomized motoneurons but are not availabl
e following avulsion. This hypothesis is tested in the present study b
y implantation of a PNS graft following the root avulsion. Results of
the present study show that implantation of a PNS graft significantly
enhances the survival of motoneurons following avulsion. Expression of
NOS due to avulsion injury is completely inhibited in all motoneurons
that regrow into the PNS graft. These results indicate that induction
of NOS in avulsed motoneurons may result from the deprivation of neur
otrophic factors produced by the PNS component, and the survival promo
ting effects of neurotrophic factors may be achieved by modifying cert
ain cellular molecules such as NOS. (C) 1994 Academic Press, Inc.