The neurochemical nature of PrPc-containing cells in the rat brain

The cellular prion protein (PrPC) is a membrane-bound glycoprotein abundantly expressed in neurons and glial cells within the CNS. The scrapie prion protein (PrPSc) is a conformationally altered isoform of PrPC that is responsible for prion diseases, also termed transmissible spongiform encephalopathies (TSE), a group of neurodegenerative diseases that affect a wide variety of mammal species, including humans. The presence of the cellular isoform of PrP is necessary for the establishment and further evolution of prion diseases and the physiological conditions where PrPC is present seems to modulate the alterations in TSE. In this work, the presence of PrPC in GABAergic, glutamatergic, nitrergic, cholinergic, serotoninergic and orexinergic populations of cells within the rat brain is examined. Our observations show that PrPC is widely expressed in a subset of neurons that contain markers of inhibitory populations of cells throughout the rat brain. The presence of PrPC in other cells types containing important neurotransmitters for the overall brain function is congruent with the imbalances reported for some of them in TSE. Within the cerebral cortex, PrPC is scarcely located in a subset of cells expressing the laminin receptor precursor (LRP) to such a low extent that suggests that other LRP-independent mechanisms actively participate during the pathogenic process. Taken together, our data demonstrate that investigation of the chemical partners of PrPC within cells gives a rational basis for the interpretation of the histopathological alterations in TSE and might help analyze some pathogenic mechanisms of PrPSc.