Distribution of the cellular prion protein (PrPC) in brains of livestock and domesticated species

Abstract

In transmissible spongiform encephalopathies (TSEs) the prion protein (PrP) plays a central role in pathogenesis. The PrP gene (Prnp) has been described in a number of mammalian and avian species and its expression product, the cellular prion protein (PrPC), has been mapped in brains of different laboratory animals (rodent and non-human primates). However, mapping of PrPC expression in mammalian species suffering from natural (bovine and ovine) and experimental (swine) TSE or in species in which prion disease has never been reported (equine and canine) deserves further attention. Thus, localising the cellular prion protein (PrPC) distribution in brain may be noteworthy for the understanding of prion disease pathogenesis since lesions seem to be restricted to particular brain areas. In the present work, we analysed the distribution of PrPC expression among several brain structures of the above species. Our results suggest that the expression of PrPC, within the same species, differs depending on the brain structure studied, but no essential differences between the PrPC distribution patterns among the studied species could be established. Positive immunoreaction was found mainly in the neuropil and to a lesser extent in neuronal bodies which occasionally appeared strongly stained in discrete regions. Overall, the expression of PrPC in the brain was significantly higher in grey matter areas than in white matter, where accumulation of PrPSc is first observed in prion diseases. Therefore, other factors besides the level of expression of cellular PrP may account for the pathogenesis of TSEs. © Springer-Verlag 2006.