Nrf2 activity is lost in the spinal cord and its astrocytes of aged mice.

We report herein a study of aging using in vitro and in vivo models. Glial fibrillary acidic protein and ferritin expression levels increased, and the levels of glutamate transporter 1 and transferrin receptor 1 decreased in aging mouse spinal cord and its astrocytes. Mitochondrial transmembrane potential in astrocytes decreased after 60 d of culture. Given the relationship between aging and loss of antioxidant tolerance capacity, we examined the expression of heme oxygenase 1 (HO1) and NAD(P)H/quinone oxidoreductase 1 (NQO1) in the old mouse astrocytes and spinal cord. Indeed, both antioxidant enzymes decreased there. Total nuclear factor E2-related factor 2, which governs basal and inducible expression of HO1 and NQO1, decreased significantly. Significantly, epigallocatechin gallate restored the Nrf2 activity.