Growth cones of regenerating adult sciatic sensory axons release axonally transported proteins.

Labelled, rapidly transported axonal proteins were shown to be released from adult frog sciatic sensory neurons, regenerating in vitro after a crush injury. The spatial distribution of the transported, released proteins could accurately be resolved by culturing the nerve on nitrocellulose paper, which trapped the released proteins. The release was located to the crush and to the entire outgrowth region. When regeneration was inhibited by adenosine, the release was limited to the crush site, implying that the release was linked to the growing axons. Other experiments suggested that the release emanated from growth cones. Furthermore, two-dimensional electrophoretical analysis of both fast axonally transported and of released proteins showed that the latter represented a selection of the transported protein species.