Department of Anesthesiology, Weifang Medical University, Weifang, Shandong 261053, China.
Chin Med J (Engl). 2013;126(10):1884-9.
There are two major pathological hallmarks of Alzheimer's disease. One is the progressive accumulation of beta-amyloid (Aβ) in the form of senile plaques; the other is hyperphosphorylated tau, causing neuronal apoptosis. Some inhalation anesthetics, such as isoflurane and desflurane, have been suggested to induce Aβ accumulation and cause AD-like neuropathogenesis. Whether intravenous anesthetics have similar effects is still unclear. We therefore set out to determine the relationship between propofol and AD-like pathogenesis.
PC12 cells were cultured in serum-free medium for 12 hours prior to drug treatment. Various concentrations from 5 µmol/L to 80 µmol/L of aggregated Aβ25-35 were added to determine a proper concentration for further study. After exposure to 10 µmol/L Aβ25-35 alone or with 20 µmol/L propofol for 6 hours, PC12 cell viability was determined by MTT assay. Western blotting and immunocytochemical staining were performed to observe the protein expression of the Bcl-2 family, tau phosphorylation at different sites, and tau protein kinases and phosphatases.
Aβ25-35 induced a decrease in PC12 cell viability in a dose-dependent manner. Exposure to 10 µmol/L Aβ25-35 for 6 hours resulted in the mild cell survival, accompanied by a decline in Bcl-2, and an increase in phosphorylation of GSK-3β and tau at different sites. Compared with the Aβ25-35 group, cells treated with propofol alone showed no significant difference, while cells co-incubated with propofol and Aβ25-35 showed a significantly higher survival rate (P < 0.01 or P < 0.05). Tau phosphorylation at Ser396, Ser404 and Thr231 and the level of GSK-3β in PC12 cells increased after exposure to 10 µmol/L Aβ25-35. Co-incubation with propofol attenuated cellular apoptosis by inhibiting tau phosphorylation.
These data indicate that propofol may protect PC12 cells from Aβ25-35-induced apoptosis and tau hyperphosphorylation through the GSK-3β pathway, therefore it may be a safer anesthesia for AD and elderly patients.
阿尔茨海默病有两个主要的病理学特征。一个是β-淀粉样蛋白（Aβ）以老年斑的形式进行渐进性积累；另一个是过度磷酸化的 tau，导致神经元凋亡。一些吸入麻醉剂，如异氟烷和地氟烷，已被认为会诱导 Aβ 积累并导致类似 AD 的神经发生。静脉麻醉剂是否有类似的作用尚不清楚。因此，我们着手确定丙泊酚与类似 AD 的发病机制之间的关系。
PC12 细胞在无血清培养基中培养 12 小时，然后用药物处理。加入从 5µmol/L 到 80µmol/L 的不同浓度的聚集 Aβ25-35，以确定进一步研究的合适浓度。单独用 10µmol/L Aβ25-35 或与 20µmol/L 丙泊酚孵育 6 小时后，通过 MTT 测定法测定 PC12 细胞活力。进行 Western blot 和免疫细胞化学染色，观察 Bcl-2 家族的蛋白表达、tau 在不同位点的磷酸化以及 tau 蛋白激酶和磷酸酶。
Aβ25-35 以剂量依赖性方式诱导 PC12 细胞活力下降。用 10µmol/L Aβ25-35 孵育 6 小时会导致轻度细胞存活，同时 Bcl-2 下降，GSK-3β 和 tau 在不同位点的磷酸化增加。与 Aβ25-35 组相比，单独用丙泊酚处理的细胞没有明显差异，而与 Aβ25-35 共孵育的细胞存活率明显更高（P<0.01 或 P<0.05）。用 10µmol/L Aβ25-35 孵育后，PC12 细胞中的 tau 在 Ser396、Ser404 和 Thr231 位点的磷酸化以及 GSK-3β 水平增加。用丙泊酚共孵育通过抑制 tau 磷酸化来减轻细胞凋亡。
这些数据表明，丙泊酚可能通过 GSK-3β 通路保护 PC12 细胞免受 Aβ25-35 诱导的细胞凋亡和 tau 过度磷酸化，因此对于 AD 和老年患者来说，它可能是一种更安全的麻醉剂。
