Long-term effects of a single dose of brain-derived neurotrophic factor on motoneuron survival following spinal root avulsion in the adult rat.

The long-term effect of a single dose of Brain-derived neurotrophic factor (BDNF) treatment on adult motoneuron survival and on expression of nitric oxide synthase (NOS) following nerve injury (avulsion) was investigated and compared with that of continuous BDNF treatment. By 6 weeks post-injury, more than 80% of motoneurons survived in animals treated with either a single dose or continuous treatment of BDNF, while only 30% of motoneurons survived in control animals (avulsion only). There were no significant differences in motoneuron survival between animals receiving a single dose and those with continuous treatment of BDNF. Additionally, the expression of NOS in avulsed motoneurons was almost completely inhibited in all BDNF treatment groups regardless of the mode of administration (single vs. continuous). These data indicate that treatment with a single dose of BDNF at the time of injury can inhibit NOS expression and provide the first evidence that in this situation BDNF has a long-term rescue effect on adult motoneuron survival after root avulsion.