Estrogens have been shown to protect neurons against various other mitochondrial toxins such as MPTP, an inhibitor of respiratory complex I [75–79]. Estrogens increase the expression of longevityassociated genes, including those encoding the antioxidant enzymes superoxide dismutase and glutathione peroxidase. As a result, mitochondria from females produce fewer reactive oxygen species [1] than those from males, an effect that may contribute to increased female longevity [80–82].