BDNF and NT-3 Rescue Sensory but Not Motoneurones Following Axotomy in the Neonate

Following axotomy of the sciatic nerve in the neonatal rat, there is loss of almost half of the sensory neurones of the lumbar dorsal root ganglia (DRG) and a similar number of spinal motoneurones. Consistent with effects in vitro, the neurotrophins BDNF and NT-3 have previously been shown to afford partial rescue of motoneurones at 1 week following axotomy. Using stereological quantitative methods we show here that at the longer time point of 3 weeks, local application of BDNF or NT-3 to the proximal stump of a lesioned sciatic nerve failed to rescue motoneurones (44% and 51% loss, respectively), but provided almost complete rescue of the loss of 41% of DRG neurones seen in L4 and L5 of vehicle-treated control animals.