title: Differential gene expression and apoptosis markers in presymptomatic scrapie affected sheep.
abstract: Neuronal loss is one of the characteristics of scrapie neuropathology. Previous analysis of brains from sheep naturally infected with scrapie that were in a terminal stage did not detect a clear induction of apoptosis, although molecular changes were evidenced. As neuronal death could be occurring early in scrapie, we developed a neuropathological and gene expression study of sheep infected with scrapie in a presymptomatic stage. The histopathology, immunolabelling of PrP(Sc), Bax and activated caspase-3, and the analysis of the expression of 7 genes involved in the regulation of the mitochondrial pathway of apoptosis were investigated in the following 4 central nervous system areas: medulla oblongata, diencephalon, frontal cortex and cerebellum. Moreover, TUNEL and NeuN immunolabelling was performed in the medulla oblongata. The PrP(Sc) immunolabelling in the four areas, as well as a neuropil spongiform change, were more evident in the terminal stage than in presymptomatic animals. Cytoplasmic Bax immunostaining was observed in the presymptomatic medulla oblongata. In contrast to symptomatic animals, the immunostaining was not extended to the hypothalamus, indicating the progression of Bax induction during the course of the disease. Although neither caspase-3 immunostaining nor the TUNEL technique detected neurons with apoptosis, NeuN-immunolabelled cell counting determined that presymptomatic animals have already suffered neuronal loss in a lower or equal degree than symptomatic animals. Finally, the gene expression profiles indicated that the mitochondrial pathway of apoptosis was activated with higher intensity in presymptomatic animals than in symptomatic sheep and confirmed the implication of genes such as BAX or AIF in the disease.
authors.affiliation: Centro de Investigación en Encefalopatías y Enfermedades Transmisibles Emergentes (CIEETE), Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Hedman
authors.forename: Jaber
authors.initials: J
authors.lastname: Lyahyai
authors.forename: Hicham
authors.initials: H
authors.lastname: Filali
authors.forename: Belén
authors.initials: B
authors.lastname: Marín
authors.forename: Carmen
authors.initials: C
authors.lastname: Serrano
authors.forename: Eva
authors.initials: E
authors.lastname: Monleón
authors.forename: Bernardino
authors.initials: B
authors.lastname: Moreno
authors.forename: Pilar
authors.initials: P
authors.lastname: Zaragoza
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Badiola
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Martín-Burriel
authors.forename: Rosa
authors.initials: R
authors.lastname: Bolea
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D051033:Apoptosis Inducing Factor / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D020287:In Situ Nick-End Labeling; D009474:Neurons / Q000473:pathology; D012608:Scrapie / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D012756:Sheep; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D051033:Apoptosis Inducing Factor; D015415:Biomarkers; D051028:bcl-2-Associated X Protein; D053148:Caspase 3