title: Neuroprotective effects of total saikosaponins of Bupleurum yinchowense on corticosterone-induced apoptosis in PC12 cells.
abstract: BACKGROUND
  The root of Bupleurum yinchowense Shan et Y. Li, a well-known medicinal plant in China, was originally documented in the "Shennong's Herbal", which is the oldest Chinese materia medica monographs. It has the action of soothing liver and relieving constraint for improving symptoms of emotional instability such as depression, anxiety and phobia. The in vivo experiment of our previous study has showed an efficacy of Total Saikosaponins (TSS) from Bupleurum yinchowense in acute stress and chronic unpredictable mild stress models. Nevertheless, there are no studies on the cytoprotection and potential mechanisms of TSS on corticosterone-induced apoptosis in PC12 cells. The present study focuses on cytoprotection against corticosterone-induced neurotoxicity in PC12 cells and its underlying molecule mechanisms of the antidepressant-like effect of TSS.
  
  
  METHODS
  The PC12 cells were treated with 250 μM corticosterone in the absence or presence of different concentrations of TSS for 24 h, then the cell viability, lactate dehydrogenase (LDH) release, Hoechst 33342 and propidium iodide (PI) double staining and the DNA fragmentation of the apoptotic PC12 cells were determined. The mitochondrial permeability transition pore (mPTP), mitochondrial membrane potential (MMP), intracellular Ca(2+) ([Ca(2+)]i) concentration and western blot analysis of caspase-3, glucose-regulated protein 78 (GRP78), growth arrest and DNA damage inducible proteins 153 (GADD-153), X-box DNA-binding protein-1 (XBP-1), Bax, Bcl-2 were investigated.
  
  
  RESULTS
  Pretreatment of PC12 cells with TSS (3.125, 6.25, 12.5, 25 μg/ml) partly reversed corticosterone-induced neurotoxicity in a dose dependent manner. TSS (25 =g/ml) reversed the increase of dead cells in the Hoechst 33342 stain, the accumulation in LDH leakage and the number of TUNEL positive cells induced by corticosterone to PC12 cells. Moreover, the cytoprotection of TSS was proved to be associated with the homeostasis of intracellular Ca(2+), the stabilization of ER stress via the down-regulation of GRP78, GADD-153, XBP-1, and the restoration of mitochondrial function, which included mPTP, MMP and caspase-3 activity. Furthermore, TSS (25 μg/ml) markedly ameliorated up-regulation of Bax and down-regulation of Bcl-2 in corticosterone-induced PC12 cells.
  
  
  CONCLUSIONS
  The result depicted that antidepressant-like effect of TSS in vivo may be associated with the cytoprotection of neuron, and the neuroprotective mechanisms were correlated with inhibiting the ER stress and the mitochondrial apoptotic pathways.
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Science, Peking Union Medical College, No 151, North Road Malianwa, Haidian District, Beijing 100193, China.
authors.forename: Zong-Yang
authors.initials: ZY
authors.lastname: Li
authors.forename: Zhi
authors.initials: Z
authors.lastname: Guo
authors.forename: Ya-Min
authors.initials: YM
authors.lastname: Liu
authors.forename: Xin-Min
authors.initials: XM
authors.lastname: Liu
authors.forename: Qi
authors.initials: Q
authors.lastname: Chang
authors.forename: Yong-hong
authors.initials: YH
authors.lastname: Liao
authors.forename: Rui-Le
authors.initials: RL
authors.lastname: Pan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D029972:Bupleurum; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003345:Corticosterone; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D016716:PC12 Cells; D051381:Rats; D012503:Saponins / Q000494:pharmacology*; D012844:Sincalide / Q000378:metabolism
chemical_list: D018696:Neuroprotective Agents; D012503:Saponins; D009828:Oleanolic Acid; D007770:L-Lactate Dehydrogenase; D053148:Caspase 3; D012844:Sincalide; D002118:Calcium; C025759:saikosaponin D; D003345:Corticosterone
keywords: Corticosterone; Endoplasmic reticulum; Mitochondria; Neuroprotection; PC12 cells; Total Saikosaponins