FOLLOWING axotomy of the sciatic nerve in the neonatal rat, there is l
oss of almost half of the sensory neurones of the lumbar dorsal root g
anglia (DRG) and a similar number of spinal motoneurones. Consistent w
ith effects in vitro, the neurotrophins BDNF and NT-3 have previously
been shown to afford partial rescue of motoneurones at 1 week followin
g 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 mot
eneurones (44% and 51% loss, respectively), but provided almost comple
te rescue of the loss of 41% of DRG neurones seen in L4 and L5 of vehi
cle-treated control animals.