[Ultrastructural study of the remyelinating process following local ethidium bromide injection in the brainstem of dexamethasone-immunosuppressed rats].
Lymphocytes are present within ethidium-bromide (EB)-demyelinated lesions in the central nervous system (CNS) and the possibility of its participation in accidental immune-mediated responses to the detached myelin sheaths can not be ruled out. This study aimed to investigate the consequences of immunosuppression with dexamethasone in CNS repair after local EB injection. Adult Wistar rats received 10 microlitres of 0.1% EB solution into the cisterna pontis. Some were treated intraperitoneally with dexamethasone (3 mg/kg/day, group I, n=15) during the experimental period; others were not immunosuppressed (group II, n=15). Animals from both groups were perfused with 4% glutharaldehyde at 7,11,15,21 and 31 days following EB injection. Brainstem slices were collected and processed for transmission electron microscopy studies. Rats from group I showed greater amounts of myelin-derived membranes than non-immunosuppressed rats (group II), suggesting a delay in the macrophagic activity of removing myelin debris. Rare lymphocytes were found. Oligodendrocyte remyelinating activity also showed a delayed pattern, with clear predominance of naked axons.
Bondan
Eduardo Fernandes
EF
Universidade Bandeirante de São Paulo, São Paulo, SP, Brasil. bondan@uol.com.br
Lallo
Maria Anete
MA
Baz
Erika Infante
EI
Sinhorini
Idércio Luís
IL
Graça
Dominguita Luhers
DL
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001933:Brain Stem / Q000187:drug effects / Q000648:ultrastructure*; D003711:Demyelinating Diseases / Q000188:drug therapy / Q000473:pathology*; D003907:Dexamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D004996:Ethidium; D007165:Immunosuppression Therapy; D008297:Male; D008855:Microscopy, Electron, Scanning; D009186:Myelin Sheath / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*; D009416:Nerve Regeneration / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D000893:Anti-Inflammatory Agents; D003907:Dexamethasone; D004996:Ethidium