Ginkgolides induced ischemic tolerance and its possible molecular mechanism: experiment with rat pheochromocytoma cell line PC12

Abstract

To explore the ischemic tolerance induced by Ginkgolides in PC12 cells and its possible molecular mechanism. An ischemic model was developed in PC12 cell line with deprivation of oxygen-glucose (OGD). PC12 cells was randomly divided into four groups: 9 hours ischemia group, 1.5 hours ischemic preconditioning + 9 hours ischemia group, Ginkgolides preconditioning + 9 hours ischemia group and control group. Cells viability was examined by MTT assay and cellular morphology was analyzed under the phase-contrast microscope. The molecular mechanism of Ginkgolides induced ischemic tolerance was pinpointedby analyzing the expression of hypoxia-inducible factor-1 alpha (HIF-1alpha) and erythropoietin (EPO). The DNA binding activities of HIF-1 in PC12 cells were examined by electrophoretic mobility shift assay. In ischemic model, the viability of PC12 cells was decreased (49.3 +/- 2.8)% after OGD for 9 hours. However, Ginkgolides pretreatment could remarkably increase the viability of PC12 cells (65.9 +/- 2.8)% (P < 0.01). Pretreatment of Ginkgolides for 24 hours could largely rescue the morphology of PC12 cells to the damage of subsequent exposure to 9 hours ischemia insult, many cellular bodies were intact and many neurites and network of PC12 cells were still exist. At molecular level, the expression of HIF-1alpha was greatly induced by Ginkgolides treatment after compared with the control group (P < 0.01). The DNA binding activities of HIF-1 in PC12 cells pretreated with Ginkgolides was also increased. And it activates its downstream target EPO, the protein expression (P < 0.01). The pretreatment of Ginkgolides could induce tolerance against ischemia in PC12 cells. The molecular mechanism of this process may involve in the activation of HIF-1alpha and the DNA binding activity of HIF-1 and its downstream target EPO.