GPX1 and Nephropathy: Regarding markers of oxidative stress, the expression of glutathione peroxidase 1 (Gpx1) remained unchanged in response to kidney damage in all experimental groups (Figure 6C), unlike nuclear factor erythroid 2-related factor 2 (Nrf2), whose expression decreased in old rats in both experimental groups compared to young rats but was not affected by R-UUO (Figure 6D).