Neuronal and non-neuronal Trk neurotrophin receptor-like proteins in Eisenia foetida (Annelida Oligochaeta)

The occurrence and distribution of Trk proteins, which are the high-affinit y signal-transducing receptors for neurotrophins, have been investigated in earthworms (Eisenia foetida) using polyclonal antibodies which map within their catalytic domain. Western-blot analysis identified major protein band s whose estimated molecular masses were consistent with those of the full-l ength Trk proteins in vertebrates. Specific immunoreactivity for TrkA-, Trk B-, and TrkC-like was observed in neuronal populations of the : dorsal cere bral, subpharyngeal and ventral cord ganglia. Furthermore, TrkA-like immuno reactivity was observed in subcutaneous neurons and nerve fibers between mu scle layers in the peripheral nervous system. TrkB- and TrkC-like immunorea ctivity was observed in the gut innervation. Non-neuronal expression of Trk B and TrkC proteins was found in epidermal cells, and TrkC-like immunoreact ivity was detected in the gut epithelium. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.