Sistema nervoso enterico e scrapie sperimentale in ovini di razza sarda con diversa suscettibilitàƒÂ genetica nei confronti della malattia

The enteric nervous system (ENS) is believed to play a key role in the pathogenesis of sheep Scrapie infection, although no information exists on the ENS cytotypes which are progressively involved, nor on the morpho-functional damage of such cells in the time course of infection. We investigated the ileal myenteric (MPs) and submucosal plexuses (SMPs) of 46 Sarda breed sheep carrying different PrP genotypes (ARQ/ARQ, ARQ/AHQ, ARQ/ARR, ARR/ARR), which had been orally dosed with Scrapie at 8 months of age and euthanized at definite time intervals post-infection (p.i.). PrPSc immunoreactivity (IR), along with pan-neuronal marker Hu C/D, nitric oxide synthase (nNOS), calbindin (CALB) and glial fibrillary acidic protein (GFAP)-IR, were evaluated by means of immunohistochemistry (IHC) and indirect immunofluorescence (IF) on paraffin-embedded sections and wholemount preparations. Eight clinically-healthy ARQ/ARQ sheep euthanized at 12-24 months p.i., along with 2 ARQ/ARQ (euthanized at 24 months p.i.) and 3 ARQ/AHQ (euthanized at 36 and 40 months p.i., respectively) clinicallyaffected sheep, showed IHC evidence of PrPSc in both their brain (obex) and ENS, especially in MPs. PrPSc deposition was fully compatible with an involvement of enteroglial cells (EGCs) and, occasionally, also with an involvement of neurons residing within ileal ENS plexuses. In conclusion, EGCs and neurons residing within ileal ENS plexuses may be likely involved in the pathogenesis of oral experimental Scrapie infection in Sarda breed sheep.