Participation of neurofilament proteins in axonal dark degeneration of rat's optic nerves.
Brain Res
; 969(1-2): 1-13, 2003 Apr 18.
Article
de En
| MEDLINE
| ID: mdl-12676359
ABSTRACT
Neurofilaments (NF) are neuronal intermediate filaments formed by three different subunits high (NF-H), medium (NF-M) and light (NF-L). They are responsible for the determination and maintenance of axon caliber. Accumulation of NF or their immunoreactive products are components of several neurodegenerative disease lesions, such as neurofibrillary tangles, Lewy bodies and the spheroids of amyotrophic lateral sclerosis. Also, cytoskeletal breakdown is one of the first ultrastructural changes occurring after nerve crush or section. In the present study, Wistar rats were subjected to bilateral enucleation to induce Wallerian degeneration of optic nerve fibers and perfused 24 h, 48 h and 1 week later. Optic nerve segments were processed for electron microscopy (EM), light microscopy immunofluorescence (LM) and immunoelectronmicroscopy (IEM) for NF subunit detection. LM for NF of control nerves showed a slightly different pattern and intensity for each subunit, with more intense staining of NF-M and NF-H and less intense staining of NF-L. This reaction did not change considerably at 48 h, but was severely reduced 1 week after enucleation. Results of EM showed fibers in (1) partial cytoskeleton degeneration or (2) watery degeneration or (3) dark degeneration. The number of dark degenerating axons was statistically higher at the latest time-interval studied. Neurofilament clumping areas and dark degenerating axons showed positive immunostaining for the three neurofilaments subunits when examined by IEM. These results suggest that dark degenerating axons develop from areas of neurofilament aggregation. We may also conclude that NF proteins participate in the process of axonal dark degeneration.
Recherche sur Google
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Nerf optique
/
Dégénérescence wallerienne
/
Protéines neurofilamenteuses
Limites:
Animals
Langue:
En
Journal:
Brain Res
Année:
2003
Type de document:
Article
Pays d'affiliation:
Brésil