The effect of axon injury on microtubule-associated proteins MAP2, 3 and 5 in the hypoglossal nucleus of the adult rat.
Microtubule-associated proteins appear to be critical elements in the stabilization of microtubules during neurite development. Axon injury results in a new burst of axonal growth activity as well as in partial dendritic involution. With this background we have examined the immunocytochemical staining pattern for microtubule-associated proteins 2, 3 and 5 in the hypoglossal nucleus of adult rats following unilateral hypoglossal nerve resection. From four days to six weeks postlesion a significant reduction in microtubule-associated protein 2-like immunoreactivity was observed in the neuropil and neuronal perikarya of the hypoglossal nucleus ipsilateral to nerve transaction. Microtubule-associated protein 5-like immunoreactivity was reduced in neuronal perikarya and neuropil four days to two weeks after injury. After six weeks microtubule-associated protein 5-like immunoreactivity had returned to normal levels. Microtubule-associated protein 3-like immunoreactivity, which was observed in glial cell perikarya and axons, but not neuronal perikarya or dendrites, appeared to be essentially unaltered. The reduced levels of microtubule-associated proteins 2 and 5 may be factors contributing to previously documented axotomy-induced dendritic retraction. The decrease in microtubule-associated protein 5 staining and absence of microtubule-associated protein 3 expression in axotomized neurons contrast with the situation in developing neurons, and demonstrate that the neuronal reaction to axon injury in mature mammals involves a specific series of events distinct from the developmental process.
Svensson
M
M
Department of Anatomy, Karolinska Institutet, Stockholm, Sweden.
Aldskogius
H
H
D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D003714:Denervation; D005260:Female; D007002:Hypoglossal Nerve / Q000378:metabolism / Q000601:surgery / Q000648:ultrastructure*; D007150:Immunohistochemistry; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009457:Neuroglia / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains
D008869:Microtubule-Associated Proteins