Reduced sympathetic sprouting occurs in dorsal root ganglia after axotomy in mice lacking low-affinity neurotrophin receptor.

Following sciatic nerve injury, sympathetic axons sprout into the L5 dorsal root ganglion (DRG). The low-affinity neurotrophin receptor (p75) is strongly expressed by glial cells in DRG following axotomy. We tested the hypothesis that p75 is involved in this sympathetic sprouting by comparing sprouting following sciatic nerve cut in wild-type (CD1) and p75 knockout mice. Twenty-one days after injury sympathetic sprouting had occurred in both mouse strains, though the extent of sprouting (measured as length of sprouts per unit area of DRG) was less in p75 knockout mice. We conclude that p75 expression enhances, but is not required for, sympathetic sprouting.