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The increase in B‐50/GAP‐43 in regenerating rat sciatic nerve occurs predominantly in unmyelinated axon shafts: A quantitative ultrastructural study
Author(s) -
Verkade P.,
Oestreicher A. B.,
Verkleij A. J.,
Gispen W. H.
Publication year - 1995
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903560310
Subject(s) - axolemma , axon , sciatic nerve , axoplasm , biology , anatomy , immunogold labelling , axoplasmic transport , immunoelectron microscopy , axon terminal , ultrastructure , gap 43 protein , neuroscience , central nervous system , immunohistochemistry , myelin , immunology
The growth‐associated protein B‐50/GAP‐43 is thought to play a crucial role in axonal growth. We investigated, by quantitative immunoelectron microscopy, whether there are differences in the subcellular distribution of B‐50 in unmyelinated and myelinated axons of intact and regenerating sciatic nerves. Adult rats received an unilateral sciatic nerve crush and were euthanized 8 days later. Nerve pieces proximal from the crush site were embedded, and B‐50 was visualized by specific B‐50 antibodies and immunogold detection in ultrathin sections. The density of B‐50 at the plasma membrane of unmyelinated axon shafts was significantly increased in the ipsilateral regenerating nerve in comparison to that of the contralateral intact nerve. In contrast, there was no significant difference in the B‐50 density at the axolemma of myelinated regenerating and intact axon shafts. In the contralateral intact nerve, more B‐50 was associated with the axolemma of unmyelinated axons than with the plasma membrane of myelinated axons. The density of axoplasmic B‐50 was similar in intact unmyelinated and myelinated axon shafts, but was higher in regenerating nerve than in intact nerve. This suggests that enhanced axonal transport of B‐50 occurs during axon outgrowth. Our study demonstrates a differential subcellular distribution of B‐50 in unmyelinated and myelinated axon shafts in both the intact and regenerating sciatic nerve, indicating a differential inducible capacity for remodeling of the axon shafts. © 1995 Wiley‐Liss, Inc.