Sex- and Brain Region-Specific Role of Cytochrome c Oxidase in 1-Methyl-4-Phenylpyridinium-Mediated Astrocyte Vulnerability

Parkinson's disease is a neurodegenerative disorder characterized by a sex and brain region specificity, showing a higher incidence in men than in women, which is caused by cell death of mainly dopaminergic neurons in the mesencephalon. Mitochondrial toxins are often used to trigger and mimic neurodegenerative processes. Thus, systemic application of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces Parkinsonian symptoms, indicating a causative or consequent involvement of mitochondria. Therefore, mitochondria of neural cells may demonstrate a sex and brain region specificity with respect to structural and functional characteristics of these organelles during toxic and degenerative processes. The application of MPTP in vivo and its toxic derivative 1-methyl-4-phenylpyridinium (MPP+) in vitro represent a well-accepted experimental model of Parkinson's disease. Aside from the known effects of MPP+ on mitochondria and neural cell survivability and with respect to the supportive role of astrocytes for neuronal function, we aimed to demonstrate the involvement of cytochrome c oxidase subunit IV isoform expression in energy and reactive oxygen species production taking part in an impairment of astrocyte survival. MPP+ caused a specific increase of COX IV-2 transcript and protein levels in male mesencephalic astrocytes, accompanied by decreased ATP and increased reactive oxygen species levels and elevated apoptotic cell death, which were more pronounced in mesencephalic than in cortical astrocytes from male than from female mice. Our data suggest that MPP+ acts on astrocytes in a sex-and brain region-specific manner involving cytochrome c oxidase isoform expression in an impairment of energy production and elevated oxidative stress levels, which represent hallmarks of neurodegenerative diseases. (C) 2011 Wiley-Liss, Inc.