Surgery-induced downregulation of hippocampal sirtuin-1 contributes to cognitive dysfunction by inhibiting autophagy and activating apoptosis in aged mice.

OBJECTIVES: Elderly patients often suffer from cognitive dysfunction following surgery. However, the mechanisms underlying this phenomenon still remain unclear. This study investigated the critical part of Sirtuin-1 (SIRT1)-mediated autophagy and apoptosis in surgery-induced cognitive impairment. METHODS: The aged (16-month-old) male C57BL/6 mice underwent anesthesia and surgery. Some mice received intraperitoneal injections of resveratrol, which is an activator of SIRT1, prior to exposure to splenectomy. To examine learning and memory behavior in different sets, the study performed a Morris water maze. Tissues from the hippocampus were harvested 1, 3 and 7 days after surgery. Western blotting and immunofluorescence analysis determined the expression of autophagy- and apoptosis- associated protein. RESULTS: This article demonstrated surgery but not anesthesia considerably affected memory behavior and downregulated SIRT1 expression in the aged mice. Interestingly, rescue of hippocampal SIRT1 expression ameliorated the cognitive impairment in the elderly mice under splenectomy. In addition, surgical trauma decreased Beclin-1 protein levels and the LC3-II/LC3-I ratio, while expression of p62, Bax and cleaved caspase-3 in hippocampal neurons increased. However, rescue of hippocampal SIRT1 expression considerably attenuated the surgery-induced downregulation of Beclin-1, increased the ratio of LC3-II/LC3-I, and decreased expression of p62, Bax, and cleaved caspase-3. CONCLUSION: These findings suggest that surgery-induced downregulation of hippocampal SIRT1 participates in cognitive impairment after surgery by inhibiting the autophagy process and activating apoptosis.

Determination of songorine in rat plasma by UPLC-MS/MS: Assay development and application to pharmacokinetic study.

An ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of songorine in rat plasma. Sample preparation was accomplished through a simple one-step deproteinization procedure with 0.2mL of acetonitrile to a 0.1mL plasma sample. Plasma samples were separated by UPLC on an Acquity UPLC BEH C18 column using a mobile phase consisting of acetonitrile-0.1% formic acid in water with gradient elution. The total run time was 3.0min and the elution of songorine was at 1.68min. The detection was performed on a triple quadrupole tandem mass spectrometer equipped with positive-ion electrospray ionization (ESI) by multiple reaction monitoring (MRM) of the transitions at m/z 358.3→340.3 for songorine and m/z 237.2→194.3 for carbamazepine (internal standard). The calibration curve was linear over the range of 1-1000ng/mL with a lower limit of quantitation (LLOQ) of 1.0 ng/mL. Mean recovery of songorine in plasma was in the range of 75.2-87.5%. The intra- and inter-day precision (RSD) was between 3.1-8.5% and 4.3-9.6% and the intra- and inter-day accuracy (RE) ranged from -4.0 to 8.9% and -9.0 to 6.7%. This method was successfully applied in pharmacokinetic study after intravenous administration of 5.0mg/kg songorine in rats.