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Synthesis of myelin proteins and ultrastructural investigations in regenerating rat sciatic nerve
Author(s) -
Alberghina M.,
Bernocchi G.,
Biggiogera M.,
Viola M.,
Karlsson J.O.,
ManfrediRomanini M.G.,
Giuffrida A.M.
Publication year - 1985
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490130410
Subject(s) - axotomy , myelin , sciatic nerve , anatomy , regeneration (biology) , remyelination , schwann cell , electron microscope , ultrastructure , chemistry , peripheral nervous system , biology , central nervous system , endocrinology , microbiology and biotechnology , physics , optics
Abstract Myelin protein synthesis, as well as ultrastructural and morphometric changes in regenerating peripheral nerve, was studied. Sciatic nerves of rats were crushed unilaterally; sham‐operated nerves of the contralateral side served as controls. For the in vivo experiments, rats were killed at selected periods after the nerves were crushed (30, 60, 90, and 120 days); seven days prior to killing, the animals were injected intravenously with L‐[4, 5− 3 H]leucine. For the in vitro experiments, proximal and distal segments of sciatic nerve and equivalent sham‐operated nerves were labeled with 3 H‐amino acid mixture 90 days after axotomy. Purified myelin was isolated from nerve segments; specific radioactivity and gel electrophoretic patterns of proteins were analyzed. Cross‐sectional electron microscope (EM) preparations of proximal, distal, and contralateral segments of nerves also were examined. Results showed that the incorporation of labeled amino acids into total myelin proteins was enhanced significantly in the distal segment of sciatic nerves at all of the periods of regeneration studied. The yield of myelin protein per mm distal nerve segment increased as regeneration proceeded. The remyelination of fibers early after nerve crush was weak, whereas it gradually attained the normal range 90–120 days after axotomy. Morphometric analysis of myelin sheath thickness of regenerating axons was consistent with the data obtained for myelin protein synthesis.