Wallerian degeneration in C57BL/6J and A/J mice: differences in time course of neurofilament and myelin breakdown, macrophage recruitment and iNOS expression.
The lower regeneration potential reported for C57BL/6J mice strain after peripheral nerve lesion may result from alterations in crucial events during Wallerian degeneration. We analysed neurofilament and myelin breakdown, macrophage recruitment, NADPH-diaphorase reaction and inducible nitric oxide synthase (iNOS) expression in transected sciatic nerves of C57BL/6J and A/J mice. The neurofilament volume density was lower in C57BL/6J strain mice at 1 and 3 days after lesion, and later equalled the density observed in A/J. C57BL/6J mice presented a high number of cells containing myelin debris, 3 and 5 days after the lesion. In both strains iNOS immunoreactivity was intense in macrophages and less evident in Schwann cells. However, a delay in macrophage recruitment and a lower percentage of iNOS-expressing macrophages on the third day were observed in C57BL/6J mice. NADPH-diaphorase reaction disclosed a similar pattern for both strains until the seventh day. However, at 5 days, cells with slender processes involving ellipsoid segments showed a well-defined cytoplasmic labelling in C57BL/6J whereas in A/J most of these cells exhibited a more granular and disperse labelling. We propose that these differences between A/J and C57BL/6J strains during Wallerian degeneration may be implicated in the lower regeneration potential observed in the latter.
de la Hoz
Cristiane L R
CL
Department of Physiology and Biophysics, State University of Campinas, SP, Brazil.
Oliveira
Alexandre L R
AL
Queiroz
Luciano de S
Lde S
Langone
Francesco
F
D000818:Animals; D002452:Cell Count; D005455:Fluorescent Antibody Technique / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D008264:Macrophages / Q000276:immunology / Q000502:physiology*; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal / Q000379:methods; D009186:Myelin Sheath / Q000502:physiology*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D016900:Neurofilament Proteins / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000032:analysis* / Q000276:immunology; D012583:Schwann Cells / Q000276:immunology; D012584:Sciatic Nerve / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D014855:Wallerian Degeneration / Q000503:physiopathology*
D016900:Neurofilament Proteins; D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase