Decursin Isolated from Angelica gigas Nakai Rescues PC12 Cells from Amyloid ß-Protein-Induced Neurotoxicity through Nrf2-Mediated Upregulation of Heme Oxygenase-1: Potential Roles of MAPK.

ABSTRACT

Decursin (D), purified from Angelica gigas Nakai, has been proven to exert neuroprotective property. Previous study revealed that D reduced A ß 25 ‒ 35-induced cytotoxicity in PC12 cells. Our study explored the underlying mechanisms by which D mediates its therapeutic effects in vitro. Pretreatment of cells with D diminished intracellular generation of ROS in response to A ß 25 ‒ 35. Western blot revealed that D significantly increased the expression and activity of HO-1, which was correlated with its protection against A ß 25 ‒ 35-induced injury. Addition of ZnPP, an HO-1 competitive inhibitor, significantly attenuated its protective effect in A ß 25 ‒ 35-treated cells, indicating the vital role of HO-1 resistance to oxidative injury. Moreover, D induced Nrf2 nuclear translocation, the upstream of HO-1 expression. While investigating the signaling pathways responsible for HO-1 induction, D activated ERK and dephosphorylated p38 in PC12 cells. Addition of U0126, a selective inhibitor of ERK, blocked D-induced Nrf2 activation and HO-1 induction and meanwhile reversed the protection of D against A ß 25 ‒ 35-induced cell death. These findings suggest D augments cellular antioxidant defense capacity through both intrinsic free radical scavenging activity and activation of MAPK signal pathways that leads to Nrf2 activation, and subsequently HO-1 induction, thereby protecting the PC12 cells from A ß 25 ‒ 35-induced oxidative cytotoxicity.