Astroglial nitration after postnatal excitotoxic damage: correlation with nitric oxide sources, cytoskeletal, apoptotic and antioxidant proteins.
Oxygen free radicals and nitric oxide (NO) participate in the pathogenesis of acute central nervous system (CNS) injury by forming peroxynitrite, which promotes oxidative damage and tyrosine nitration. Neuronal nitration is associated with cell death, but little is known of the characteristics and cell fate of nitrated astrocytes. In this study, we have used a postnatal excitotoxic lesion model (intracortical NMDA injection) and our aims were (i) to evaluate the temporal and spatial pattern of astroglial nitration in correlation with the neuropathological process and the sources of NO; and (ii) to establish, if any, the correlation among astrocyte nitration and other events such as expression of cytoskeletal proteins, antioxidant enzymes, and cell death markers to cope with nitration and/or undergo cell death. Our results show that after postnatal excitotoxic damage two distinct waves of nitration were observed in relation to astrocytes. At 24 h post-lesion, early-nitrated astrocytes were found within the neurodegenerating area, coinciding with the time of maximal cell death. These early-nitrated astrocytes are highly ramified protoplasmic cells, showing diffuse glial fibrillary acidic protein (GFAP) content and expressing inducible NOS. At later time-points, when astrogliosis is morphologically evident, nitrated hypertrophied reactive astrocytes are observed in the penumbra and the neurodegenerated area, displaying increased expression of GFAP and vimentin cytoskeletal proteins and of metallothionein I-II and Cu/Zn superoxide dismutase antioxidant proteins. Moreover, despite revealing activated caspase-3, they do not show TUNEL labeling. In summary, we show that nitrated astrocytes in vivo constitute a subpopulation of highly reactive astrocytes which display high resistance towards oxidative stress induced cell death.
Acarin
Laia
L
Unit of Histology, School of Medicine, Department of Cell Biology, Physiology and Immunology, Institute of Neurosciences, Universitat Autonoma Barcelona, Bellaterra 08193, Spain. laia.acarin@uab.es
Peluffo
Hugo
H
Barbeito
Luis
L
Castellano
Bernardo
B
González
Berta
B
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism*; D001930:Brain Injuries / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D008668:Metallothionein / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009498:Neurotoxins; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D051381:Rats; D020318:Rats, Long-Evans; D013482:Superoxide Dismutase / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism*
D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; D009498:Neurotoxins; C002744:3-nitrotyrosine; D014443:Tyrosine; D008668:Metallothionein; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; D013482:Superoxide Dismutase