VALUTAZIONE QUALI-QUANTITATIVA DELL’INNERVAZIONE DELLE PLACCHE DEL PEYER ILEALI IN OVINI DI RAZZA SARDA INDENNI O AFFETTI DA SCRAPIE

Although Peyer’s patches (PPs) and the enteric nervous system (ENS) play a key role in early sheep scrapie pathogenesis, little is known on the kinetics of ENS plexuses colonization. This study was aimed at quali-quantitatively evaluating ileal PP innervation in 29 Sarda breed ovines (12 scrapie-free, 2 months-old lambs, 4 ARQ/ARQ, 4 ARR/ARQ and 4 ARR/ARR, respectively; 12 scrapie-free, 2-4 years-old sheep, 3 ARQ/ARQ, 7 ARR/ARQ and 2 ARR/ARR, respectively; 5 ARQ/ARQ scrapie-affected sheep). Terminal ileum was collected and processed for routine histology from all animals under study. Ileal PP innervation was immunohistochemically evaluated by means of an anti-PgP9.5 (pan-neuronal marker) polyclonal antibody (Ab) and of an anti-TH (sympathetic innervation marker) monoclonal Ab. Moreover, PrPSc immunohistochemistry was carried out by means of the F99/97.6.1 monoclonal Ab. Quite a developed network of fibres was detected within PPs, almost exclusively located in the interfollicular lymphoid tissue and stromal component. Intrafollicular fibres could be very rarely observed, with no apparent differences in the innervation rate being found between scrapie-free and scrapie-affected sheep. In adult animals, both scrapie-free and scrapie-affected, nerve fibres could be detected close to the follicle-associated epithelium. Furthermore, the TH+ component was very limited. In conclusion, no significant differences in ileal PP innervation seem to exist in relation to PrP genotype, age and PrPSc deposition within PP follicles. Key words: scrapie, sheep, Peyer’s patches, enteric nervous system, pathogenesis