To determine the functional role of cerebral Nrdp1 in response to OGD treatment, we examined the expression of Nrdp1 in OGD-treated primary rat cerebral cortical neurons. The cells were exposed to OGD for 1, 3, or 6 h before analyzing Nrdp1 mRNA and protein levels. Real time RT-PCR analysis showed that Nrdp1 mRNA expression was increased in cerebral cortical neurons after exposing to OGD for 1 h and was further increased at 6-h OGD, while no significant difference was seen between 1-h OGD and 3-h OGD (Figure 2A). Western blot analysis showed that Nrdp1 protein levels were significantly increased in cerebral cortical neurons after exposing to OGD for 3 h and 6 h, but not for 1 h (Figure 2B). To further verify the above findings, we assayed the expression of Nrdp1 in PC12 cells exposed to the same OGD treatment as above. Real time RT-PCR analysis showed that Nrdp1 mRNA expression was increased in PC12 cells after exposing to OGD for 3-h and 6-h OGD, but not for 1 h (Figure 2C). Western blot analysis showed that Nrdp1 protein levels were significantly increased in PC12 cells after exposing to OGD for 6 h, but not for 1 h and 3 h (Figure 2D). These data demonstrate that OGD induces Nrdp1 upregulation in cerebral cortical neurons as well as PC12 cells in a time-dependent manner.