IMMUNOHISTOCHEMICAL LOCALIZATION OF CELL-ADHESION MOLECULES AND CELL-CELL CONTACT PROTEINS DURING REGENERATION OF THE RAT OPTIC-NERVE INDUCED BY SCIATIC-NERVE AUTOTRANSPLANTATION

Background: The central nervous system neurons of adult mammals are kn own to regenerate into peripheral nerve autograft, The localization of cell adhesion molecules and cell-cell contact proteins were studied d uring axonal regeneration induced by sciatic nerve autotransplantation . Methods: A sciatic nerve autograft was anastomosed to the proximal s tump of the transected rat optic nerve, Immunofluorescence microscopy, thin sectioning, and immunoelectron microscopy with the preembedding method and ultrathin cryosections were used to localize cell adhesion molecules (L1; neural cell adhesion molecule, NCAM; myelin-associated glycoprotein, MAG) and cell-cell contact proteins (connexins 32, 43, Z O-1) at 3 days to 4 weeks postoperation. Results: Most regenerating ax ons contacted astrocytes in the optic nerve and Schwann cells in the g raft. Immunoreactivity of NCAM was widely distributed along the surfac e of axons, astrocytes, Schwann cells, and perineurial cells. The L1 i mmunoreactivity was confined to the interface of axon-astrocyte and of axon-Schwann cell. MAG immunoreactivity was seen at the interface of axon and myelin within the graft. Connexins 32, 43, and ZO-1 immunorea ctivities were observed at contact sites between axons and Schwann cel ls within the graft. Conclusions: Cell adhesion molecules (L1, NCAM, M AG) are localized at the cell surface of regenerating axons, astrocyte s, and Schwann cells during optic nerve regeneration elicited by perip heral nerve graft. Cell-cell contact proteins (connexins 32, 43, ZO-1) are present at the interface between axons and Schwann cells in the g raft. Our results suggest that these molecules are involved in cell ad hesion events during optic nerve regeneration. (C) 1996 Wiley-Liss, In c.