OBJECTIVETo study the tolerance to ischemia induced by Acanthopanax Senticosus Saponins (ASE) in PC12 cells and the involved mechanism.

METHODSAn ischemic model was developed in PC12 cell line by treatment with oxygen-glucose deprivation. The effects of ASE pretreatment on tolerance of PC12 cells to ischemia were evaluated by MTT assay and analysis of cellular morphology. The expression of hypoxia-inducing factor (HIF)-1alpha, erythropoietin (EPO) after the pretreatment with ASE was detected by Western blotting. The DNA binding activities of HIF-1 in PC12 cells with the pretreatment of ASE were demonstrated by using electrophoretic mobility shift assay (EMSA).

RESULTSIn ischemia model, the viability of PC12 cells was decreased to (49.12 +/- 3.22)% after oxygen-glucose deprivation for 9 hours. However, ASE (50 microg/ml) pretreatment could remarkably increase the viability of PC12 cells by (67.97 +/- 2.92)%. There were significant differences between the experimental group and control group (F = 473.67, P < 0.01). The cellular morphology showed that PC12 cells exposed for 7 days to nerve growth factor (NGF) exhibited round, smooth cell bodies with normal processes and that processes formed extensive network. At 9 hour after ischemia, cell bodies of many PC12 cells were found shrinken, the processes were disrupted and network disappeared. However, pretreatment with ASE (50 microg/ml) could largely prevent the morphological damage to PC12 cells that would have caused by subsequent exposure to 9 h ischemic insult, many cellular bodies were intact and many processes and network of PC12 cells still existed. The expression of HIF-1alpha increased after pretreatment with ASE shown by Western blot. There were significant differences between the experimental group and control group (F = 167.18, P < 0.01). The DNA binding activities of HIF-1 in PC12 cells after pretreatment with ASE was significantly increased, and it could activate the expression of EPO (F = 128.37, P < 0.01).

CONCLUSIONSThe pretreatment with ASE could induce tolerance against ischemia in PC12 cells. The elevated expression and increased DNA binding activity of HIF-1alpha, the overexpression of its downstream target EPO may be the molecular mechanism in tolerance of PC12 cells to ischemia induced by ASE pretreatment.