Changes occur in the ability to promote axonal regeneration as the post-injury period increases.
This study tested whether adult rat brain stem neurons could respond to growth or trophic factors provided after an extended post-injury period. The number of neurons that regenerated their axon into a peripheral nerve graft following exposure to ciliary neurotrophic factor (CNTF) 8 weeks after a cervical lesion was comparable to the number regenerating after exposure to CNTF 4 weeks after injury. In contrast, there was a significant decrease of 50% in the number of regenerating neurons following exposure to basic fibroblast growth factor (bFGF) 8 weeks after injury compared with the number regenerating after treatment with bFGF 4 weeks after injury. These results indicate that some factors are effective promoters of regeneration only if provided within a defined post-injury period.
Houle
J D
JD
Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock 72205, USA.
Ye
J H
JH
D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D001930:Brain Injuries / Q000503:physiopathology*; D001933:Brain Stem / Q000502:physiology* / Q000503:physiopathology; D020934:Ciliary Neurotrophic Factor; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D009414:Nerve Growth Factors / Q000494:pharmacology; D009416:Nerve Regeneration / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012154:Reticular Formation / Q000187:drug effects / Q000293:injuries / Q000502:physiology; D012584:Sciatic Nerve / Q000187:drug effects / Q000502:physiology* / Q000637:transplantation*; D013997:Time Factors
D020934:Ciliary Neurotrophic Factor; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D016222:Fibroblast Growth Factor 2