Expression of GAP-43 in normal and regenerating nerves in the frog.

A polyclonal antiserum to chicken, growth-associated protein-43 (GAP-43), raised in rabbit, was shown to recognize a molecule with similar properties to GAP-43 in frogs. Using this antiserum, GAP-43 immunoreactivity was shown to be present throughout the brain and white matter of the spinal cord of larval frogs, but became restricted to specific regions in the adult frog central nervous system. In the peripheral nervous system, GAP-43 was present in normal tadpole and adult axons. After cutting the adult sciatic nerve, GAP-43 slowly disappeared from axons in the distal stump, but appeared in Schwann cells and other (uncharacterized) cells. The constitutive expression of GAP-43 in the adult frog sciatic nerve may be related to the phenomenon of remodelling of motor end-plates, which is known to occur throughout life in frogs.