title: Changes in the expression pattern of the nitrergic system of ovine cerebellum affected by scrapie.
abstract: The constitutive and inducible isoforms of nitric oxide synthase (NOS) and the end-product of nitration, nitrotyrosine, were analyzed by immunohistochemistry, Western blotting, and enzymatic activity in sheep at different stages of the prion disease, scrapie. Four groups were studied: 1) nonaffected (control), 2) preclinical, 3) clinical, and 4) terminal. Constitutive neuronal NOS (nNOS) was the most abundant isoform present in cerebellar neurons of the sheep. Expression of nNOS increased in preclinical animals but diminished in the late stages of the disease. The Purkinje cells that usually are not immunoreactive for this protein became immunopositive in the clinical phase. In unaffected sheep, the inducible isoform (iNOS) was slightly positive in the Purkinje cells. As the disease progressed, the immunoreactivity of Purkinje neurons for iNOS increased. At the final stages, numerous iNOS-positive microglial cells were found in the molecular layer. There was a basal level of protein nitration in the cerebellum of unaffected sheep, especially in the molecular layer. As the disease progressed, the distal prolongations of the Purkinje cells and the astroglia became immunoreactive for nitrotyrosine. Our results suggest that the nitrergic system reacts to the progression of spongiform diseases and may be part of their pathogenesis mechanism.
authors.affiliation: Department of Neuroanatomy and Cell Biology, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Ana Patricia
authors.initials: AP
authors.lastname: Fernández
authors.forename: Julia
authors.initials: J
authors.lastname: Serrano
authors.forename: José
authors.initials: J
authors.lastname: Rodrigo
authors.forename: Eva
authors.initials: E
authors.lastname: Monleón
authors.forename: Marta
authors.initials: M
authors.lastname: Monzón
authors.forename: Antonia
authors.initials: A
authors.lastname: Vargas
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Badiola
authors.forename: Ricardo
authors.initials: R
authors.lastname: Martínez-Murillo
authors.forename: Alfredo
authors.initials: A
authors.lastname: Martínez
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002531:Cerebellum / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D007150:Immunohistochemistry / Q000379:methods; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D012608:Scrapie / Q000473:pathology*; D012756:Sheep; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: C002744:3-nitrotyrosine; D014443:Tyrosine; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II