The Common Inhalation Anesthetic Isoflurane Induces Caspase Activation and Increases Amyloid beta-Protein Level In Vivo

Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
Annals of Neurology (Impact Factor: 9.98). 12/2008; 64(6):618-27. DOI: 10.1002/ana.21548
Source: PubMed


An estimated 200 million patients worldwide have surgery each year. Anesthesia and surgery have been reported to facilitate emergence of Alzheimer's disease. The commonly used inhalation anesthetic isoflurane has previously been reported to induce apoptosis, and to increase levels and aggregation of Alzheimer's disease-associated amyloid beta-protein (Abeta) in cultured cells. However, the in vivo relevance has not been addressed.
We therefore set out to determine effects of isoflurane on caspase activation and levels of beta-site amyloid precursor protein-cleaving enzyme (BACE) and Abeta in naive mice, using Western blot, immunohistochemistry, and reverse transcriptase polymerase chain reaction.
Here we show for the first time that a clinically relevant isoflurane anesthesia (1.4% isoflurane for 2 hours) leads to caspase activation and modest increases in levels of BACE 6 hours after anesthesia in mouse brain. Isoflurane anesthesia induces caspase activation, and increases levels of BACE and Abeta up to 24 hours after anesthesia. Isoflurane may increase BACE levels by reducing BACE degradation. Moreover, the Abeta aggregation inhibitor, clioquinol, was able to attenuate isoflurane-induced caspase-3 activation in vivo.
Given that transient insults to brain may lead to long-term brain damage, these findings suggest that isoflurane may promote Alzheimer's disease neuropathogenesis and, as such, have implications for use of isoflurane in humans, pending human study confirmation.

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Available from: Robert D Moir, Sep 16, 2014
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    • "Firstly, NIRS oximeters were put on forehead and reflected the condition of superficial cerebral cortex, so it might miss embolism, hypoperfusion and desaturation far from superficial cortex [46] . Secondly, Neurotoxicity such as neuroinflammation and Aβ generation also contribute to POCD474849, which affect the predictive performance of ScO 2 . Thirdly, even if absolute value of 50 and 80 % of baseline were regarded as safe limits for ScO 2 to prevent cerebral ischemia, cognitive dysfunction were still observed in the present and previous studies [13]. "
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    ABSTRACT: Background Postoperative cognitive dysfunction (POCD) is a frequent complication in elderly patients undergoing major non-cardiac surgery, but its etiology is still unclear. Cerebral oxygen saturation (ScO2) represents the balance of cerebral oxygen supply and demand. The aim of present study was to evaluate the relationship between perioperative ScO2 and POCD, and to verify the hypothesis that the value of ScO2 after multiple perioperative influential factors could predict POCD in elderly patients undergoing total knee arthroplasty (TKA). Methods Seventy eight Patients aged more than 65 years undergoing elective TKA with intrathecal anesthesia were enrolled. Cognitive functions were assessed one day before and 6 days after surgery, and POCD were defined according to ISPOCD. Demographics were recorded. Perioperative ScO2, blood pressure (BP), blood gas analysis and other clinical data were monitored and recorded, then the decrease of ScO2, BP and PaO2 after influential factors were calculated. Results POCD occurred in 15 patients (19.2 %). BP decreased after anesthesia induction and tourniquet deflation, and PaO2 decreased after cement implantation was higher in POCD group. ScO2 of POCD group is significantly lower than non-POCD group (P < 0.05), and the absolute value and percentage decrease of ScO2 became significant between two groups after multiple influential factors. ScO2 after all influential factors (anesthesia induction, cement implantation and tourniquet deflation) had the best predictive performance for POCD (AUC = 0.742), and the optimal threshold was 66.5 %. Conclusions Perioperative ScO2 of patients with POCD is lower than patients without POCD. ScO2 after multiple perioperative influential factors could be an effective predictor for POCD, which reveal an important role of ScO2 decrease in the development of POCD and provide possible treatment target.
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    • "used to detect β - Actin ( 42 kDa ) . Western blot quantification was performed as described by Xie et al . ( 2008 ) . One hundred percent of the protein level changes on the Y - axis of the figures refer to the control condition for the purpose of comparison with experimental conditions ."
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    ABSTRACT: There is a need to develop animal models to study postoperative delirium. Inattention is one of the symptoms of delirium. Increases in the levels of α-synuclein and S100β have been reported to be associated with delirium. Therefore, we set out to determine the effects of surgery plus general anesthesia on the behavioral changes (including loss of attention) in mice and on the levels of α-synuclein and S100β in the brain tissues of these mice. C57BL/6J mice (2- to 8-months-old) had a simple laparotomy plus isoflurane anesthesia. The behavioral changes, including attention level and the speed of movements, were determined 12, 24, and 48 h after the surgery plus anesthesia in the mice. The levels of α-synuclein and S100β in the cortex of these mice following the surgery plus anesthesia were determined by Western blot analysis. We found that there was a loss of attention at 24, but not 12 or 48 h following the surgery plus anesthesia (49% ± 5 vs. 33% ± 2.9, P = 0.011, N = 12) in the mice without significantly affecting the speed of their movements. There were increases in the levels of total α-synuclein (139% ± 33.5 vs. 100% ± 13.7, P = 0.037, N = 6) and S100β (142% ± 7.7 vs. 100% ± 6, P = 0.002, N = 6) in the cortex of the mice 12 h following the surgery plus anesthesia. These findings suggested that the surgery plus isoflurane anesthesia might induce behavioral and biochemical/cellular changes associated with delirium. We could use the surgery plus anesthesia in mice to develop an animal model to study postoperative delirium.
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    • "As such, western blots were performed to examine changes to Aβ, but no monomeric species were detected. This may have been due to the time dependent nature of changes to this protein found by others [22] where mouse Aβ levels were unchanged at 6 or 12 hours post anaesthesia yet increased at the 24-hour point. Alternatively, and most likely, this may be due to the known technical difficulties associated with detecting endogenous mouse Aβ [33]. "

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