Time course and age dependence of motor neuron death following facial nerve crush injury: Role of fibroblast growth factor

Peripheral nerve crush injury (PNCI) has been used for many years in adult animals to study central and peripheral changes related to regeneration acr oss the injury site. While these adult animals experience full recovery wit h no neuronal cell loss following PNCI, it has been noted that the injury i n perinatal animals is followed by retrograde neuronal cell death. The pres ent study determines, in mice of different postnatal ages, the degree to wh ich motor neurons are vulnerable to PNCI induced cell death and examines th e rate of neuronal loss. Animals of 4 days of age and younger were found to be significantly more vulnerable to motor neuron cell death following PNCI , There also was a proportional relationship between age at injury and fina l motor neuronal survival and an inverse relationship between age at injury and rate of neuronal cell death following injury. In addition a proportion al relationship was observed between the expression level of acidic fibrobl ast growth factor within motor neurons and the resistance to PNCI induced n euronal death. It was also found that PNCI in an environment that contained higher levels of FGFs (either in mice treated with acidic FGF or in transg enic mice that overexpress basic FGF) significantly decreases neuronal cell death following early postnatal injury. (C) 1999 Academic Press.