Oxidative stress and
antioxidants play an important role in
neurodegenerative diseases. However, the exact participation of
antioxidants in the evolution of
prion diseases is still largely unknown. The aim of this study was to assess brain levels of
coenzyme Q (CoQ), an endogenous lipophilic
antioxidant, and the
antioxidant/
pro-oxidant status by determining oxidative damage to
proteins and
lipids after intracerebral
bovine spongiform encephalopathy (BSE)
infection of transgenic mice expressing bovine
prion protein (PrP). Our results indicate that, whereas the ratio between the two CoQ homologues present in mice (CoQ(9) and
CoQ(10)) is not altered by
prion infection during the course of the disease, significant increases in total CoQ(9) and
CoQ(10) were observed in BSE-infected mice 150 days after inoculation. This time point coincided with the first manifestation of PrP(Sc) deposition in nervous tissue. In addition, CoQ(9) and
CoQ(10) levels, neuropathological alterations, and PrP(Sc) deposition in nervous tissues underwent further increases as the illness progressed.
Lipid and
protein oxidation were observed only at the final stage of the disease after clinical signs had appeared. These findings indicate upregulation of CoQ(9)- and CoQ(10)-dependent
antioxidant systems in response to the increased oxidative stress induced by
prion infection in nervous tissue. However, the induction of these
endogenous antioxidant systems seems to be insufficient to prevent the development of the illness.