Growth-associated protein GAP-43 and nerve cell adhesion molecule in sensory nerves of cornea.

We used dual-wavelength fluorescence microscopy and monoclonal antibodies to growth-associated protein (GAP-43) and nerve cell adhesion molecule (N-CAM) to identify these proteins in nerve fibers of normal rat and rabbit corneas. Overlapping immunoreactivity of GAP-43 and N-CAM was evident along nerve fibers of rabbit corneal sections, suggesting that GAP-43 is constitutively expressed in these sensory nerves. The immune reaction of monoclonal antibody to GAP-43 and [125I]protein A was used to quantitate relative amounts of GAP-43 in the normal cornea and in a cornea subjected to a de-epithelializing wound. Collectively these findings imply that GAP-43 is axoplasmically transported from cells in the trigeminal (or superior cervical) ganglion to the cornea. Moreover, these data indicate that GAP-43 appears to be involved in the remodeling of corneal nerves that is necessary for normal innervation.