Methods Preparation and Incubation of Neuronal PC12 Cells Neuronal PC12 cells were obtained from the Key Laboratory of Neurobiology, Institute of Medicine, Shanghai Institutes for Biological Sciences, Chinese ” Academy of Sciences and cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum and 7.5% horse serum in a humidified incubator at 37uC and 5% CO2. For the survival experiments, the PC12 cells were seeded on 96-well plates in culture medium 
supplemented with 10 nM mouse 7S nerve growth factor . After 3 days, additional NGF was added. After 6 days of culture with NGF, more than 95% of the cells appeared to be morphologically differentiated with neurites at least twice the length of the cell body diameter; the cells were exposed to combined oxygen and glucose deprivation at 0, 0.5, 1, 3, 6 and 12 h on the seventh day. Oxygen and Glucose Deprivation Treatment and Assessment of PC12 Cells Injury Combined oxygen and ” glucose deprivation was performed as described previously. Briefly, ischemia was introduced by a buffer exchange to Hanks solution, which is an ischemia-mimetic solution and subsequently, the culture dishes were placed in a hypoxic incubator chamber equilibrated with 95% N2/5% CO2 at 37uC for 0.5, 1, 3, 6 and 12 h. The buffered Hanks solution was MedChemExpress 2883-98-9 previously gassed with 95% N2/5% CO2 for 30 min. Arterial blood gas tensions include PaO2, PaCO2, PH and GI. MAP, mean arterial pressure; PaO2, arterial oxygen pressure; PaCO2, arterial carbon dioxide pressure; GI, glucose. a Controlled parameter. doi:10.1371/journal.pone.0035324.t001 and propofol were preincubated for 10 min before and during OGD stimulation. 3-MA , a specific inhibitor of autophagosome formation, was added as a positive control. For the western blot analysis of the effects of propofol on autophagy-related proteins, the PC12 cells were cultured in 60 mm dishes, harvested and probed for autophagy-related proteins after 0, 0.5, 1, 3, 6 and 12 h of OGD. Transmission Electron Microscopic Analyses of Autophagosomes in PC12 Cells after OGD Injury The PC12 cells were cultured in 60 mm dishes and treated with OGD for 0.5, 1, 3, 6 and 12 h. After treatment, the cells were fixed with 4.0% paraformaldehyde in phosphate-buffered saline and then post-fixed with 2.0% glutaraldehyde in 0.1 mol/L PBS and preserved at 4uC for further processing. When the processing resumed, the cells were post-fixed in 1% osmium tetroxide in PBS, dehydrated in graded alcohols, embedded in Epon 812, sectioned with an ultramicrotome, and stained with uranyl acetate and lead citrate. The sections were examined using a transmission electron microscope. of PC12 cells, the cells were treated with propofol and 3-MA during OGD. LDH leakage was measured 6 h after OGD. Briefly, after OGD treatment, the supernatant of the cell culture was harvested. The PC12 cells were rinsed with PBS and lysed with 1% Triton X-100 at 37uC for 30 min. The supernatants and cell lysates were prepared following the manufacturer’s instructions for the LDH assay using a cell viability assay kit. The absorbance value at 440 nm was determined with an automatic multiwell spectrophotometer. LDH leakage was calculated using the following formula: LDH leakage = / 6 100%. Cell Viability Assay PC12 cell viability was determined with a 3–2,5-diphenyltetrazolium bromide assay 6 h after OGD treatment in accordance with a previously described method. To examine the contribution of propofol to OGD-induced PC12 cell death, PC12 c